Bathtub Royale hotfix

Fixed a bug where too many viewers joining at the same time would crash the game in BtR mode
Increased BtR duck health from 5 to 10
Enabled movement in the bath before starting race for a more even battle
Added a medicine cabinet/mirror in the bathroom
Fixed a UI issue where selecting the Bathtub Royale map would select Gentle Swim instead
Race! button now defaults to Gentle Swim to match UI