Do not rely on no-secondary for movable tests

Currently, the code in Loader.hs marks as un-movable any instances
which don't have a secondary. This is not valid for any shared storage
templates, so let's remove that check completely. The initial state of
the instance will reflect correctly the movable status, based on the
disk template of the instance, so we don't need to re-do this check.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>