webadmin: Hide Network QoS sub-tab

*** This patch is 3.3 branch only ***

Hide the Network QoS sub-tab from the UI. Since the Vnic Profiles were
not introduced in 3.3, Network QoS has no use.

Change-Id: Ifb2f22b9f5e6e240d42c23a433d2e75ec571fafd
Signed-off-by: Ofri Masad <omasad@redhat.com>