NIFI-9331 Correct ThreadUtils handling of Locked Stacked Frame

[exceptionfactory]

Description of PR

NIFI-9331 Corrects ThreadUtils.createStackTrace() handling of MonitorInfo.getLockedStackFrame() in cases where the method returns null. Changes include using Objects.equals() to handle comparison of nullable arguments, removing unused arguments, and adding a unit test for ThreadUtils to confirm expected behavior. This change corrects behavior of the LongRunningTaskMonitor and other components that gather thread information.

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[pvillard31]

Merged, thanks @exceptionfactory