[whakomatic]

For #1628

XGAIPlayer.InvalidateUnitToMove ended the AI turn whenever the move list emptied.
When an unrevealed pod skipped its turn, SkipGroupTurn removed every pod member, so each removal could end the turn, and each end of turn submitted a SkipTurn that copied every unit on the AI side into the history.
Long tactical missions grew until the save stopped loading.

This removes the end turn check from InvalidateUnitToMove. The function signature is unchanged, so mods that call or override it are unaffected. Skipped units still lose their action points, and the turn still ends once no AI unit can act.

Tested in a debug build over 6 alien turns with two unrevealed pods:

• every pod member had 0 action points after its SkipUnit
• no WaitingForNewStates watchdog timeouts; each alien turn ended correctly
• pod followers stayed with their leader's patrol