[ALICE3] Mark variables as maybe unused

[ktf]

No description provided.

[ktf]

Currently broken. Merging. Someone should review why they are actually unused.

[mhemmer-cern]

I think theisig variable below mcDecision is also sometimes unused when removing the mcDecision (I just tried removing the unused once locally). Do they need [[maybe_unused]] as well in those cases here to not trigger variable unused or is this safe?

[ktf]

I think [[maybe_unused]] taints all derived variables, so no. In any case locally my linter does not complain, let's see.

[mhemmer-cern]

Okay, thank you for quickly fixing this issue.