[ATR-21910][ATR-21910] Trig Cost online concurrency fixes

Resolve two issues seen at P1 in MT mode.

1. Multiple slots could access the thread-hash -> thread-counter map concurrently. The mutex protection was only per-slot. Resolved by adding a small global lock to this map lookup.
2. We encountered hash collisions online. As we only collect monitoring data here, this is not too critical and the exception can be caught and discarded with only a DEBUG message. A unit test was added around this.

This merge request affects 2 packages:

• Trigger/TrigConfiguration/TrigConfHLTUtils
• Trigger/TrigMonitoring/TrigCostMonitorMT

Adding @mark ,@orlando ,@cmorenom ,@asonay as watchers

added DQ Trigger master review-pending-level-1 labels

resolved all threads

CI Result SUCCESS (hash b162399f)

	Athena	AthSimulation	AthGeneration	AnalysisBase
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 19151]

Tests pass, and changes look reasonable. L1 approving.

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit de3375e3

added sweep:ignore label