Fix song select buttons not working after attempting to force-exit when mod select is open

[Joehuu]

• Closes Pre-exit dialog abruptly cuts the mod select transition and blocks some function keys on the next carousel load #38146

When pressing Alt-F4, the mod select overlay never closes and does this in order:

SetButton();
clearActiveOverlayContainer(); // inside SetButton()

Pressing home or exiting via Esc runs clearActiveOverlayContainer() first, and it doesn't trigger the bug because the hiddenButtonsContainer container gets cleared before the temporarilyHiddenButtons list does. Unsure why SetButtons() needs to clear temporarilyHiddenButtons. There's no regression when I tested.

Hide()ing the overlay on the screen's OnExiting() is also a fix. MultiplayerMatchSongSelect already has freeModSelect.Hide().

I've applied both above as one makes sure the bug doesn't happen anymore when forgetting to Hide() the overlay on the screen's OnExiting() and the other fixes the no pop out animation.