Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1488998

Description of problem:

No notification regarding Discovery Host should be visible when there is no one available (see screenshot).

How reproducible:

Always

Steps to Reproduce:
1. Create a Discovery Host
2. Delete the Discovery Host

Actual results:

There is a notifications regarding discovery host even in its absence.

Expected results:

No notifications regarding discovery host.