webadmin: StorageView tabs - remove redundant right border

IscsiStorageView.ui.xml:
Removed redundant right border (has been added horizontal tabs).

Screenshot-of-defect: http://imgur.com/OiHMJ6t

Change-Id: Id8756d2f5538385d6f1092f76327dd0ff95ca417
Signed-off-by: Daniel Erez <derez@redhat.com>