Description of problem:

Setting a default_domain_suffix for IDM based authentication would reduce an effort to type in the @domain while authenticating.

Version-Release number of selected component (if applicable):
Satellite 6.12

How reproducible:

Steps to Reproduce:
1. Configure direct AD authentication or IPA authentication from https://access.redhat.com/documentation/en-us/red_hat_satellite/6.11/html/administering_red_hat_satellite/configuring_external_authentication_admin#Configuring_Direct_AD_Integration_with_GSS_Proxy_admin
2. Check the /etc/sssd/sssd.conf as no default domain suffix is configured
3. Having this we can query user without a domain suffix.

Actual results:
An end-user would have to type the user@domain.com syntax to login to Satellite

Expected results:
We can reduce this effort by setting a default_domain_suffix to the current domain that the host is joined to.

Additional info:

Under [sssd] section adding default_domain_suffix = example.com to achieve this