Make stop/disable of apparmor work on all SLE systems

The existing code to disable apparmor on SUSE systems only worked for
recent openSUSE / SLE releases.  On SLE12 (at least), aa-enabled and
aa-teardown are not available, so instead use systemd's interface for
stop/disable.  However on newer releases, systemctl stop apparmor is a
no-op:

    https://www.suse.com/releasenotes/x86_64/SUSE-SLES/15/#fate-325343
    https://gitlab.com/apparmor/apparmor/merge_requests/81
    https://build.opensuse.org/package/view_file/openSUSE:Leap:15.2/apparmor/apparmor.service?expand=1

So we still need to call aa-teardown if it's available.

Change-Id: I8d99c8d743cc1935324e2e4fcb67efaa5241199e
1 file changed