In https://jira.camunda.com/browse/OPT-4039, we add a new query parameter for filtering definition keys by Camunda sources that can be used in event based processes. Once this has been added, we should migrate all frontend usage to using this parameter instead of the existing excludeEventProcesses query parameter.

ATs:

• We use the new parameter to fetch Camunda definition keys that can be used in event based processes
• We no longer use the excludeExternalProcesses query parameter at all (this will be deprecated in https://jira.camunda.com/browse/OPT-4040)