hooks: Move sanlock upgrade hook to post-upgrade

Previously the sanlock upgrade loogic was run on boot, and that broken
vdsm's boot on el7/systemd based systems.
Now the logic is run post-upgrade and not at boot time.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1156369
Change-Id: I53d63c393e884901eb45f1ac38e8bf2795dbaeb7
Signed-off-by: Fabian Deutsch <fabiand@fedoraproject.org>