Backup code added in MDL-56310 incorrectly checks moodle/role:safeoverride for users who already have moodle/role:override

The logic is supposed to be that if you have moodle/role:override, then you can overrid any capability, not just 'safe' ones, and so whether you have moodle/role:safeoverride or not should be irrelevant.

Except that, MDL-56310 messed this up (meaning that when you backup and restore a bunch of courses as part of your year-end process, you lose random capabilities which are then hard to find and manually re-instate )