Add ATLAS_CHECK_THREAD_SAFETY to TrkVertexOnTrack

Removing mutable and adding ATLAS_CHECK_THREAD_SAFETY to TrkVertexOnTrack

This merge request affects 3 packages:

• Tracking/TrkEvent/TrkCaloCluster_OnTrack
• Tracking/TrkEvent/TrkPseudoMeasurementOnTrack
• Tracking/TrkEvent/TrkVertexOnTrack

added Tracking master review-pending-level-1 labels

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-23391-2019-05-14-06-58
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST 38394]

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

merged

mentioned in commit 03165b3d

added sweep:ignore label