Description of problem:
Subscription-manager release --unset doesn't reset the client information on Red Hat Satellite

Version-Release number of selected component (if applicable):
Satellite 6.x

How reproducible:
Unset Subscription-manager release on the client and check info on satellite.

Steps to Reproduce:
1. Subscription-manager release --unset
2. Subscription-manager release --show
3. Subscription-manager facts --update

Actual results:
Release Version remains the same on the satellite DB

Expected results:
Release Version should be updated on the satellite

Additional info:
Also Subscription-manager facts --update doesn't refresh release information

QE Tracker for https://issues.redhat.com/browse/SAT-23992
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2269998