webadmin: disable scan alignment for non-block SDs

VMs -> Disks sub-tab:
disable scan alignment action for non-block storage domains
(as it's applicable only for block domains).

Disks main-tab:
scan alignment will be blocked on canDoAction in a separate patch.

Change-Id: I2f4150f72332fb071a90001e63858a5212a0db0a
Bug-Url: https://bugzilla.redhat.com/1046031
Signed-off-by: Daniel Erez <derez@redhat.com>