webadmin: move disks popup - fix alignment

Remove redundant/unused panels, labels and styles
(for fixing alignment when using Chrome).

Change-Id: Ibbb9b6cb8b316245463955c43ae30e490224a7b6
Bug-Url: https://bugzilla.redhat.com/893984
Signed-off-by: Daniel Erez <derez@redhat.com>