22.0-redundant_code_removal-InDetPhysValMonitoring

In the context of ATLIDTRKCP-255, and having introduced unit tests to ensure functioning. This MR removes redundant legacy code, in particular:

• Plain text (.hdef) file definition as input to the HistogramDefinitionSvc
• The unused Xerces-SAX event driven parser (only the DOM one is used)
• Unused test code, since replaced by the unit tests

This merge request affects 1 package:

• InnerDetector/InDetValidation/InDetPhysValMonitoring

Adding @goetz ,@sroe as watchers

added InnerDetector master review-pending-level-1 labels

CI Result SUCCESS (hash 8e94e40f)

	Athena	AthSimulation	AnalysisBase	AthGeneration
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
AnalysisBase: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 14540]

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

merged

mentioned in commit 772b6813

added sweep:ignore label