Drop obsolete ITruthIncident::updateChildParticle(...) method

This method is no-longer used since we switched to using the Shadow GenEvent approach to quasi-stable particle simulation.

This merge request affects 3 packages:

• Simulation/ISF/ISF_Core/ISF_Event
• Simulation/ISF/ISF_Core/ISF_Services
• Simulation/ISF/ISF_Geant4/ISF_Geant4Event

Affected files list will not be printed in this case

Adding @lmijovic ,@jchapman as watchers

added Simulation main review-pending-level-1 labels

CI Result SUCCESS (hash cf027de3)

	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-EL9 10016] (remote access info)

Code changes look fine from L1 perspective and the CI succeeded. Cheers, L1 shifter

removed review-pending-level-1 label

added review-approved label

merged

mentioned in commit 3fdb12c1