Bugfix: Beat Up checks the user's party instead of always checking player's party

[td76099]

@Piefrenzy on Discord

Beat Up worked correctly when the player used it, but when the enemy used it it was looking at the player's party to determine the number of hits. This means that a wild Pokemon in single battles could hit the player up to 6 times when it should only be once.

Now, enemy Pokemon in single battles will hit once, enemy Pokemon in double battle will hit twice (or once if partner dead), and trainer battles hit the expected amount based on Pokemon remaining in either singles/doubles.

Video of it working:

https://github.com/pagefaultgames/pokerogue/assets/85713900/f8740a82-1c8a-406e-b729-460b48ac7e6c