Description of problem:

If a host has a hostgroup with OpenSCAP Proxy, the host cant have empty value for OpenSCAP Proxy

Steps to Reproduce:

1.Create a host group with only a name and OpenSCAP Proxy, name - "HG1"

2.in a host, set the hostgroup to "HG1", set OpenSCAP Proxy to be empty, save

3.Open the host edit page again

Actual behavior:
 OpenSCAP Proxy is set 

Expected behavior:
 OpenSCAP Proxy is empty

Business Impact / Additional info:

Can remove it if host group is unsassigned