DelegateExecutionContext.getCurrentDelegationExecution() does not provide current execution when used in signal expression

Environment (Required on creation):

• Any Camunda engine version
• BPMN process with an intermediate signal event using an expression to call DelegateExecutionContext.getCurrentDelegationExecution()

Description (Required on creation; please attach any relevant screenshots, stacktraces, log files, etc. to the ticket):

When an intermediate signal event uses an expression like ${Somebean.getSignalName()} to call DelegateExecutionContext.getCurrentDelegationExecution(), the call returns null.

Steps to reproduce (Required on creation):

• Create a BPMN process including an intermediate signal event
• The signal event calls some delegation class via expression (e.g., ${Somebean.getSignalName()})
• The delegation code executes and returns the result of the following call: DelegateExecutionContext.getCurrentDelegationExecution()
• The result is null

To reproduce the issue, you can simply run the spring boot application: https://github.com/rtkohl/signal-name-test

Observed Behavior (Required on creation):

When running the example project mentioned above, first a service task calls the problematic code. This works fine. The current execution is returned.
The delegate for the signal activity returns null for the following call:

String activityId = DelegateExecutionContext.getCurrentDelegationExecution().getCurrentActivityId();

Expected behavior (Required on creation):

The activity id of the signal event is returned.

Root Cause (Required on prioritization):

The intermediate signal activity is a scope. This means that a new execution is created for it.

This is done here: https://github.com/camunda/camunda-bpm-platform/blob/cab8852cda1822b7d4551122b70bc56fa7f2f2b8/engine/src/main/java/org/camunda/bpm/engine/impl/pvm/runtime/operation/PvmAtomicOperationCreateScope.java#L40
The new execution is never set for the DelegateExecutionContext. The call still returns the process instance execution.

Solution Ideas (Optional):

Set the newly created execution as context execution on the delegate invocation. Then the context is updated in the DefaultDelegateInterceptor: https://github.com/camunda/camunda-bpm-platform/blob/cab8852cda1822b7d4551122b70bc56fa7f2f2b8/engine/src/main/java/org/camunda/bpm/engine/impl/delegate/DefaultDelegateInterceptor.java#L89

Hints (optional):