Changed the message line of RouterInUse class

Implements: Changed the message line of RouterInUse class,
so user will not get confused with active or inactive ports
while deleting the router.

Closes-Bug: #1236372
Change-Id: I7a82550e2c6051f9e4940a8f1dd4401059e0a8d8
(cherry picked from commit 238689570145fdafe8e61967bb56133f167d39ab)
Merge "Changed the message line of RouterInUse class" into milestone-proposed