Multiple instance tasks result in the loss of event subprocess listening.

**Describe the bug**
In the model shown in the diagram below, before the timer boundary event of taskA is triggered, the subprocess event in the model can respond to `RuntimeService.signalEventReceived("signal_A")` arbitrarily. However, after the timer boundary event of taskA is triggered and the signal is thrown, the subprocess event no longer responds, even if the timer event of taskB cannot make it respond. Note that taskA must be a multiple instance, otherwise everything works fine.

**Expected behavior**
Because the signal thrown by the taskA task is processed by the non-interrupting event subprocess, it can still receive the signal.

**Code**

**Additional context**

org.flowable
flowable-spring-boot-starter-process
6.8.0