rgw/admin: guard bilog autotrim on non-exporting (archive) zones

rgw/admin: guard bilog autotrim on non-exporting (archive) zones

The background sync-log-trim thread already skips bucket trim on zones whose
sync module does not export data , but the admin command had no equivalent
guard, so running it on an archive zone could delete instance metadata the
zone is meant to retain.

So, refuse the command on non-exporting zones unless --yes-i-really-mean-it is
given.

Fixes: https://tracker.ceph.com/issues/78364
Signed-off-by: Oguzhan Ozmen <oozmen@bloomberg.net>