ConcurrentModificationException SERVER - game error

Happened at the start of a turn, the player lost connection and this popped up, not the first time it happened, but he used different decks

```
Error type: SERVER - game error

Client version: 1.4.55-V3 (build: 2024-12-16 20:14)
Java version: 1.8.0_201
Default charset: UTF-8

Game error occurred:

java.util.ConcurrentModificationException
Server version: 1.4.55-V3 (build: 2024-12-16 20:14)
Stack trace:
java.util.ArrayList$Itr.checkForComodification(ArrayList.java:911)
java.util.ArrayList$Itr.next(ArrayList.java:861)
mage.util.CardUtil.deepCopyList(CardUtil.java:1992)
mage.util.CardUtil.deepCopyObject(CardUtil.java:1944)
mage.abilities.TriggeredAbilities.(TriggeredAbilities.java:65)
mage.abilities.TriggeredAbilities.copy(TriggeredAbilities.java:318)
mage.game.GameState.(GameState.java:169)
mage.game.GameState.copy(GameState.java:289)
mage.game.GameStates.save(GameStates.java:23)
mage.game.GameImpl.saveState(GameImpl.java:808)
mage.game.GameImpl.bookmarkState(GameImpl.java:938)
mage.game.GameImpl.playPriority(GameImpl.java:1695)
mage.game.turn.Step.priority(Step.java:67)
mage.game.turn.Phase.playStep(Phase.java:205)
mage.game.turn.Phase.play(Phase.java:91)
mage.game.turn.Turn.play(Turn.java:137)
mage.game.GameImpl.playTurn(GameImpl.java:1153)
mage.game.GameImpl.play(GameImpl.java:1060)
mage.game.GameImpl.start(GameImpl.java:1036)
mage.server.game.GameWorker.call(GameWorker.java:35)
mage.server.game.GameWorker.call(GameWorker.java:16)
java.util.concurrent.FutureTask.run(FutureTask.java:266)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
java.lang.Thread.run(Thread.java:750)

```

Start with mage.util.CardUtil.deepCopyList and mage.abilities.TriggeredAbilities, following the stack into GameState.copy and GameImpl.bookmarkState during priority handling. Reproduce the server game error if possible and trace the concurrent modification in the state-copy path. Done means the reported exception no longer occurs while saving game state.

Written by the indexing model from the issue text.