fix: bepu, removal of collidables while running a contact event leaves contact tracking in an unexpected state

[Eideren]

PR Details

See title, doing this causes some issues in the tracking of contact events, refactoring the logic to avoid this.

Related Issue

None reported afaict

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My change requires a change to the documentation.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have built and run the editor to try this change out.