Remove unused ComputeRandomRadianRotation function and '%' suffix for compounds in patch details

[ender-titan1]

Brief Description of What This PR Does

Removes the unused ComputeRandomRadianRotation function from SpawnSystem.cs and also removes the '%' format from compounds in the patch details menu.

Related Issues

Closes #3883
Closes #3909

Progress Checklist

Note: before starting this checklist the PR should be marked as non-draft.

• PR author has checked that this PR works as intended and doesn't
  break existing features:
  https://wiki.revolutionarygamesstudio.com/wiki/Testing_Checklist
  (In progress - all I have at the moment is GitPod.)
• Initial code review passed (this and further items should not be checked by the PR author)
• Functionality is confirmed working by another person (see above checklist link)
• Final code review is passed and code conforms to the
  styleguide.

Before merging all CI jobs should finish on this PR without errors, if
there are automatically detected style issues they should be fixed by
the PR author. Merging must follow our
styleguide.

[hhyyrylainen]

You should leave the default PR checklist intact so that we can track what has been checked for the PR.

[ender-titan1]

Ok, got it

[hhyyrylainen]

The Jetbrains fail is that it wants you to put CurrentCulture as parameter to the ToString calls.
Also the change to the Godot project file should be reverted because it's very suspicious to me.

[hhyyrylainen]

The code change looks fine to me, just need someone to playtest this next.

[athariqk]

Works fine.