webadmin: hide refresh triangle icon on sub-tabs

Refresh options/menu triangle icon is redundant for
sub-tabs since isTimerDisabled == true.
I.e. refresh button for sub-tabs is relevant
only for manual refresh.
Hence, hide refresh menu icon on sub-tabs.

Affected sub-tabs:
Hosts -> Network Interfaces
Storage -> Images

Change-Id: I5c467e94bc7a2562bac4711b6b64e5f0b6699b53
Signed-off-by: Daniel Erez <derez@redhat.com>