Adjust concurrent test for MariaDB Galera cluster scenario

19:35:04.031 [Thread-351] ERROR org.camunda.bpm.engine.context - ENGINE-16004 Exception while closing command context: 
### Error committing transaction.  Cause: java.sql.SQLTransactionRollbackException: (conn:85) Deadlock found when trying to get lock; try restarting transaction
### Cause: java.sql.SQLTransactionRollbackException: (conn:85) Deadlock found when trying to get lock; try restarting transaction
org.apache.ibatis.exceptions.PersistenceException: 
### Error committing transaction.  Cause: java.sql.SQLTransactionRollbackException: (conn:85) Deadlock found when trying to get lock; try restarting transaction
### Cause: java.sql.SQLTransactionRollbackException: (conn:85) Deadlock found when trying to get lock; try restarting transaction
	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30) ~[mybatis-3.5.3.jar:3.5.3]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.commit(DefaultSqlSession.java:226) ~[mybatis-3.5.3.jar:3.5.3]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.commit(DefaultSqlSession.java:217) ~[mybatis-3.5.3.jar:3.5.3]
	at org.camunda.bpm.engine.impl.db.sql.DbSqlSession.commit(DbSqlSession.java:335) ~[classes/:na]
	at org.camunda.bpm.engine.impl.cfg.standalone.StandaloneTransactionContext.commit(StandaloneTransactionContext.java:67) ~[classes/:na]
	at org.camunda.bpm.engine.impl.interceptor.CommandContext.close(CommandContext.java:195) ~[classes/:na]
	at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:119) [classes/:na]
	at org.camunda.bpm.engine.impl.interceptor.ProcessApplicationContextInterceptor.execute(ProcessApplicationContextInterceptor.java:70) [classes/:na]
	at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:33) [classes/:na]
	at org.camunda.bpm.engine.test.concurrency.ConcurrencyTestCase$1.run(ConcurrencyTestCase.java:62) [test-classes/:na]
	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_181]
Caused by: java.sql.SQLTransactionRollbackException: (conn:85) Deadlock found when trying to get lock; try restarting transaction
	at org.mariadb.jdbc.internal.util.exceptions.ExceptionMapper.get(ExceptionMapper.java:160) ~[mariadb-java-client-1.6.3.jar:na]
	at org.mariadb.jdbc.internal.util.exceptions.ExceptionMapper.getException(ExceptionMapper.java:118) ~[mariadb-java-client-1.6.3.jar:na]
	at org.mariadb.jdbc.MariaDbStatement.executeExceptionEpilogue(MariaDbStatement.java:247) ~[mariadb-java-client-1.6.3.jar:na]
	at org.mariadb.jdbc.MariaDbStatement.executeInternal(MariaDbStatement.java:322) ~[mariadb-java-client-1.6.3.jar:na]
	at org.mariadb.jdbc.MariaDbStatement.execute(MariaDbStatement.java:373) ~[mariadb-java-client-1.6.3.jar:na]
	at org.mariadb.jdbc.MariaDbConnection.commit(MariaDbConnection.java:635) ~[mariadb-java-client-1.6.3.jar:na]
	at sun.reflect.GeneratedMethodAccessor25.invoke(Unknown Source) ~[na:na]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
	at org.apache.ibatis.datasource.pooled.PooledConnection.invoke(PooledConnection.java:245) ~[mybatis-3.5.3.jar:3.5.3]
	at com.sun.proxy.$Proxy18.commit(Unknown Source) ~[na:na]
	at org.apache.ibatis.transaction.jdbc.JdbcTransaction.commit(JdbcTransaction.java:71) ~[mybatis-3.5.3.jar:3.5.3]
	at org.apache.ibatis.executor.BaseExecutor.commit(BaseExecutor.java:244) ~[mybatis-3.5.3.jar:3.5.3]
	at org.apache.ibatis.executor.CachingExecutor.commit(CachingExecutor.java:119) ~[mybatis-3.5.3.jar:3.5.3]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.commit(DefaultSqlSession.java:223) ~[mybatis-3.5.3.jar:3.5.3]
	... 9 common frames omitted
Caused by: java.sql.SQLException: Deadlock found when trying to get lock; try restarting transaction
Query is: COMMIT
	at org.mariadb.jdbc.internal.util.LogQueryTool.exceptionWithQuery(LogQueryTool.java:112) ~[mariadb-java-client-1.6.3.jar:na]
	at org.mariadb.jdbc.internal.protocol.AbstractQueryProtocol.executeQuery(AbstractQueryProtocol.java:167) ~[mariadb-java-client-1.6.3.jar:na]
	at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source) ~[na:na]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
	at org.mariadb.jdbc.internal.failover.AbstractMastersListener.invoke(AbstractMastersListener.java:361) ~[mariadb-java-client-1.6.3.jar:na]
	at org.mariadb.jdbc.internal.failover.FailoverProxy.executeInvocation(FailoverProxy.java:216) ~[mariadb-java-client-1.6.3.jar:na]
	at org.mariadb.jdbc.internal.failover.FailoverProxy.invoke(FailoverProxy.java:209) ~[mariadb-java-client-1.6.3.jar:na]
	at com.sun.proxy.$Proxy17.executeQuery(Unknown Source) ~[na:na]
	at org.mariadb.jdbc.MariaDbStatement.executeInternal(MariaDbStatement.java:316) ~[mariadb-java-client-1.6.3.jar:na]
	... 20 common frames omitted
19:35:04.033 [main] ERROR org.camunda.bpm.engine.test - ASSERTION FAILED: junit.framework.AssertionFailedError: Unexpected interruption
junit.framework.AssertionFailedError: Unexpected interruption
	at junit.framework.Assert.fail(Assert.java:57) ~[junit-4.12.jar:4.12]
	at junit.framework.TestCase.fail(TestCase.java:227) [junit-4.12.jar:4.12]
	at org.camunda.bpm.engine.test.concurrency.ConcurrencyTestCase$ThreadControl.join(ConcurrencyTestCase.java:157) ~[test-classes/:na]
	at org.camunda.bpm.engine.test.concurrency.ConcurrencyTestCase$ThreadControl.waitUntilDone(ConcurrencyTestCase.java:149) ~[test-classes/:na]
	at org.camunda.bpm.engine.test.concurrency.ConcurrencyTestCase$ThreadControl.waitUntilDone(ConcurrencyTestCase.java:143) ~[test-classes/:na]
	at org.camunda.bpm.engine.test.concurrency.ConcurrentHistoryCleanupUpdateOfFailingJobTest.testFailedHistoryCleanupJobUpdate(ConcurrentHistoryCleanupUpdateOfFailingJobTest.java:89) ~[test-classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
	at junit.framework.TestCase.runTest(TestCase.java:176) [junit-4.12.jar:4.12]
	at junit.framework.TestCase.runBare(TestCase.java:141) [junit-4.12.jar:4.12]
	at org.camunda.bpm.engine.impl.test.AbstractProcessEngineTestCase.runBare(AbstractProcessEngineTestCase.java:115) ~[classes/:na]
	at junit.framework.TestResult$1.protect(TestResult.java:122) [junit-4.12.jar:4.12]
	at junit.framework.TestResult.runProtected(TestResult.java:142) [junit-4.12.jar:4.12]
	at junit.framework.TestResult.run(TestResult.java:125) [junit-4.12.jar:4.12]
	at junit.framework.TestCase.run(TestCase.java:129) [junit-4.12.jar:4.12]
	at junit.framework.TestSuite.runTest(TestSuite.java:252) [junit-4.12.jar:4.12]
	at junit.framework.TestSuite.run(TestSuite.java:247) [junit-4.12.jar:4.12]
	at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:86) [junit-4.12.jar:4.12]
	at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:365) [surefire-junit4-2.22.2.jar:2.22.2]
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeWithRerun(JUnit4Provider.java:273) [surefire-junit4-2.22.2.jar:2.22.2]
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:238) [surefire-junit4-2.22.2.jar:2.22.2]
	at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:159) [surefire-junit4-2.22.2.jar:2.22.2]
	at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:384) [surefire-booter-2.22.2.jar:2.22.2]
	at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:345) [surefire-booter-2.22.2.jar:2.22.2]
	at org.apache.maven.surefire.booter.ForkedBooter.execute(ForkedBooter.java:126) [surefire-booter-2.22.2.jar:2.22.2]
	at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:418) [surefire-booter-2.22.2.jar:2.22.2]