TrkGeometry Layers: Remove unneeded virtual methods/ mark methods as final.

TrkGeometry Layers: Remove unneeded virtual methods. Also mark methods as final where applicable/possible

This merge request affects 8 files:

• Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/ConeLayer.h
• Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/CylinderLayer.h
• Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/DiscLayer.h
• Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/Layer.h
• Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/NavigationLayer.h
• Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/PlaneLayer.h
• Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/SubtractedCylinderLayer.h
• Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/SubtractedPlaneLayer.h

Adding @amorley as watcher

added Tracking master review-pending-level-1 labels

CI Result SUCCESS (hash e808b76e)

	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 23714]

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

merged

mentioned in commit 637f2e58

added sweep:ignore label