Modify EngineStateMonitor to use built-in Zeebe functionality

[remcowesterhoud]

Description

In camunda/camunda#8510 a mechanism was introduced in Zeebe which can be used to track if
processing has reached the end. We should use this instead of our own implementation in the EngineStateMonitor to check if the engine is idle.

[remcowesterhoud]

@pihme If you'd like it'd be cool if you could revisit the EngineStateMonitor

[pihme]

Removed myself from assignee, as I haven't been working on it in the last few weeks and unclear if and when I will continue