Address Thread-checker warnings in `Charginos`, `Gauginos` and `Sleptons` packages

Creation of G4ParticleDefinition objects occurs during the initialization of Geant4 which is done in a single thread. The syntax used in the Charginos, Gauginos and Sleptons packages follows the syntax used in Geant4:
https://gitlab.cern.ch/atlas-simulation-team/geant4/-/blob/v10.6.3.4/source/particles/leptons/include/G4Electron.hh
https://gitlab.cern.ch/atlas-simulation-team/geant4/-/blob/v10.6.3.4/source/particles/leptons/src/G4Electron.cc
For now we mark the static s_theInstance/theInstance variables as ATLAS_THREAD_SAFE until such time as the syntax is updated to something neater on the Geant4 side.

Tagging @christos and @fwinkl

This merge request affects 3 packages:

• Simulation/G4Extensions/Charginos
• Simulation/G4Extensions/Gauginos
• Simulation/G4Extensions/Sleptons

Affected files list will not be printed in this case

Adding @jchapman as watcher

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

added 1 commit

• 0226abfc - Add explanatory comments where ATLAS_THREAD_SAFE is used

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resolved all threads

Build area was cleaned as per request posted in the DB. The full software build will be performed

Build area was cleaned as per request posted in the DB. The full software build will be performed

There were multiple CI triggers for this MR and commit. The system ignored duplicates but the GitLab pipeline status may incorrectly show the job as failed. Once the remaining job finished running, the CI results will be posted as usual.

This merge request affects 3 packages:

• Simulation/G4Extensions/Charginos
• Simulation/G4Extensions/Gauginos
• Simulation/G4Extensions/Sleptons

Affected files list will not be printed in this case

Adding @jchapman as watcher

CI Result SUCCESS (hash 6bc5eca2)

	Athena	AthSimulation
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
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 62178]

CI Result SUCCESS (hash 0226abfc)

	Athena	AthSimulation
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
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 62180]

Approving - L1

removed review-pending-level-1 label

added review-approved label

merged

mentioned in commit 1b70328f

added sweep:ignore label