Process instance suspend itself, the process instance can never be activated.

**Describe the bug**
When **I use a execution listener to suspend the current process instance**, all the executions, tasks, jobs will be suspended.
However, after the execution listener completed, **the process seems to create a new execution or task, and the new execution or task has not been suspended.**
By this time, **the process instance can never be activated**, beacuse when I try to activate the process, the new task has not been suspended, so it also can not be activated, and throw the FlowableException "Cannot set suspension state active for xxx : already in state active."
**What's more, I can't even delete the current process instance, because it is suspended.**

**Expected behavior**
However, I use Signal Intermediate Catching Event to implement my requirement.
But I think it is better to do a validation when execute the suspend commend, and if a process instance try to suspend itself, throw an exception to warn the user this error usage.