webadmin: label group in setup networks shouldn't have tooltip

Mouse over label group on setup networks displays the last displayed
tooltip. Shouldn't display anything.

Change-Id: I6c46d850f5452b7318e52c6ea5494a3ab2c6a3da
Bug-Url: https://bugzilla.redhat.com/1064432
Signed-off-by: Alona Kaplan <alkaplan@redhat.com>