TruthRivetTools: const/mutable fixes

Some minor thread-checker fixes.

This merge request affects 1 package:

• Generators/TruthRivetTools

This merge request affects 3 files:

• Generators/TruthRivetTools/Root/HiggsTruthCategoryTool.cxx
• Generators/TruthRivetTools/TruthRivetTools/HiggsTemplateCrossSections.h
• Generators/TruthRivetTools/TruthRivetTools/HiggsTruthCategoryTool.h

added Generators master review-pending-level-1 labels

The system determined that CI tests (with names matching "^CITest_Trigger.*$") are not needed for this code change. They are not run. This is not an indicator to restart the job.

CI Result SUCCESS (hash 8db412e4)

	Athena	AthSimulation	AthGeneration	AnalysisBase	AthAnalysis	DetCommon
externals
cmake
make
tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
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
AthAnalysis: number of compilation errors 0, warnings 0
DetCommon: number of compilation errors 0, warnings 0
For experts only: Jenkins output CI-MERGE-REQUEST-CC7 58567(https://atlas-sit-ci.cern.ch/job/CI-MERGE-REQUEST-CC7/58567/)

Approved
Albert (L1)

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

merged

mentioned in commit fc0ac289

added sweep:ignore label