Fix pistons breaking when head is replaced

[VanJackal]

Fixes #2956 by adding a check for if the block was changed before calling affectNeighborsAfterRemoval

[me4502]

Thank you for looking into this! 😀

I can't investigate or review too deeply right now as I'm just replying on my lunch break, but from memory the entire "dirty" / update process here should be gated by a "changed check" coming from MC itself further up, unless something has changed within MC.

Either way if that check itself no longer functions, it should be fixed at the top level rather than in here. There are niche situations where we want to force these to occur always (eg, //update command), and it's not the only change that should be skipped during a no-op change during typical edits.