Disable supervision before trying to remove supervising profile.

This should fix issues with deleting the PIN when user restrictions are
still in place.

(Note this also includes some diffs from ktfmt)

Bug: 406082832
Flag: android.app.supervision.flags.enable_supervision_settings_screen
Test: atest SupervisionDeletePinPreferenceTest
Change-Id: If3664cc9d09cdb4e3e9f63e4932e0aa371aeef41