Logprep config validation runs endlessly if many logmessages are being sent

[ppcad]

Logprep test config runs endlessly after being finished if many log messages have been sent.
One way to reproduce this is by having many Logprep rules that use the deprecated lucene syntax.
This will create log messages during loading the config.

This problem does likely extend to all Logprep features that load the config and want to close Logprep after they are finished.

This could be circumvented by printing less deprecation messages or disabling the logging while verifying the config, but this would be just a work-around.