MuonG4SD: Fix uninitialized reads in tests.

Some of the test code was trying to construct identifiers using invalid inputs, resulting in out-of-bounds array reads and unpredictable results.

This merge request affects 1 package:

• MuonSpectrometer/MuonG4/MuonG4SD

Adding @rosati ,@nkoehler ,@wleight as watchers

added MuonSpectrometer Simulation master review-pending-level-1 labels

CI Result SUCCESS (hash 4d33ab3b)

	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 1
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 19892]

Warning related to offline CI server

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

merged

mentioned in commit ecee44c1

added sweep:ignore label