avoid warnings in vertex truth match tool in case there are no vertices to match

The InDetVertexTruthMatchTool::match method currently throws a WARNING if after checking the vertices in the event it has not found at least one case of an attached track particle collection. Unfortunately, it also does so if there are no vertices to match in the first place (for example, on single particle MC), in which case this check fails by construction.

This MR makes the tool exit without complaining in case there are no vertices to match (either empty collection or just a dummy vertex), avoiding the warning as well as skipping execution of any downstream code.

@jojungge, thank you for the nice picture of Jürgen Habermas in !32488 (merged)!

Tagging @npetters for information

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• 6990bd47 - add rejection of contains filled only with a dummy vertex

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unmarked as a Work In Progress

This merge request affects 1 package:

• InnerDetector/InDetValidation/InDetTruthVertexValidation

Adding @goetz ,@sroe as watchers

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CI Result FAILURE (hash 6990bd47)

	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 13311]

Changes look good to me. Failure of Trigger_athena_MC-test is a known issue. Approving.

Xiaozhong (L1)

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

merged

mentioned in commit e6a2486f

added sweep:ignore label