PunchThroughG4: Add missing override keywords and fix other cppcheck issues

Tadej Novakrequested to merge
tadej/athena:ptg4-override into 24.0

Add missing override keywords in the new PunchThroughG4 classes and fix some other issues.

Let's keep 24.0 in sync and fix it also here.

/cc @ssnyder @tsulaia @jchapman @mumohdso

Edited by Tadej Novak

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