webadmin: Minor adjustment for remove external network message

Change-Id: If65a2cf50bb89b29988913fd8801b4ce32ef6e95
Bug-Url: https://bugzilla.redhat.com/1101068
Signed-off-by: Moti Asayag <masayag@redhat.com>
(cherry picked from commit ac985911a69317a6a974f3a0b754b5cddf177bad)