Bad behavior using Parallel Gateway with 2 end events

**Describe the bug**
I create a simple workflow with 2 parallel **NON** EXCLUSIVE AND **ASYNC** branches
(I want to be able to execute both branches really in parallel), each one finishing by its own end event.


When I start the workflow, everything seems fine according to the log (no exception, all branch messages displayed)

and the workflow diagram shows it is finished


But according to the UI and the DB, it isn't the case:
UI - still running
DB - EXECUTION:
DB - RU_ACTINST: **ALL activities with an END_TIME**

**Expected behavior**
I would like to:
1. see that there's a problem (Optimistic Exception) in the log
2. see a retry on the branch(es) that failed (if any)
3. no more see the workflow as running (no more EXECUTION, no more history in ACTINST)

_BTW we can't configure an end event like we do for a gateway (which may be exclusive and async), so no way to handle a possible optimistic exception locally at this end event. The only possibility to be able to retry only this end event is to add a dummy task which may be exclusive and async and so fail then retry without impact on the previous steps in the branch. **Adding exclusive and async attributes to an (end) event would be useful.**_

**Code**
The corresponding APP ZIP file
[TEST_PARALLEL_END.zip](https://github.com/flowable/flowable-engine/files/10360632/TEST_PARALLEL_END.zip)

**Additional context**
Flowable 6.7.2 in Tomcat 8