Owner/Assignee cannot be overridden by a StartProcessInstanceInterceptor

[epictecch]

The process start capabilities have been extended with #3449. It allows to set the owner and assignee directly at the process start.
Furthermore, the developer has foreseen the possibility to override these properties by a StartProcessInstanceInterceptor but does not use these overridden values.
See
https://github.com/flowable/flowable-engine/blob/main/modules/flowable-engine/src/main/java/org/flowable/engine/impl/util/ProcessInstanceHelper.java#L236
and
https://github.com/flowable/flowable-engine/blob/main/modules/flowable-engine/src/main/java/org/flowable/engine/impl/util/ProcessInstanceHelper.java#L239
Instead of using the variables ownerId and assigneeId, the values from startInstanceBeforeContext.getOwnerId() and startInstanceBeforeContext.getAssigneeId() should be used.

Additional context:
Note that the pull request #3449 is superseded by my own pull request #3407. If it is planned to use the #3407 feature, you might want to remove the #3449 feature and in that case, this bug report gets obsolete.