Decrease amount of spawns in cave

[Milopetilo]

Summary

Bugfixes "Stop spawning too many monsters in a cave"

Purpose of change

Closes #76597

Describe the solution

Lowered the amount of monsters in GROUP_CAVE and used place_monster to spawn them.

Describe alternatives you've considered

More bats?

Testing

Game loads, cave is no longer a clown car

Additional context

Might do an audit on all the caves, they always felt a bit outdated to me.