webadmin: hide refresh interval tool-tip on sub-tabs

In continuation of commit 7f1591bd56df7cbee99297a72da491a4053626ba,
the "Refresh Interval: {0} sec" tool-tip should be hidden
when the refresh time is diabled.

Change-Id: I6c92b0c7f33738e50ffe9f858b37fe1cca506bbb
Signed-off-by: Daniel Erez <derez@redhat.com>