Improve the concurrent behaviour of the tracking event processor.

[gklijs]

Turns out there were a few edge cases left. I also restructured a bit, to make both workers more the same. Now when a worker 'switches jobs' it will always be from the cleanup/finally.

The main left over problem was that the AtomicBoolean for the workLauncherRunning was set from the worker thread. So it could happen that it would switch to true, after calling start(), which in turn prevented the thread to be stopped at shutdown() which in turn caused an error when calling start() again, since it was not properly shutdown, as expected.

Additionally a removeThread(String name) method was added, where the expectation is that it will never actually log the message, but would provide valuable information if it does.

This was locally tested as fix for #2293, 10.000 times stopping and starting worked without problems, where the latest release would give an error around 30-50 times.

[sonarcloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

0.0% Coverage
0.0% Duplication

[smcvb]

Looks good to me 👍