Current installation flow is:

• ipa-client-install does IPA domain auto-detection using DNS by default.
• Auto-detection fails because DNS configuration is broken OR there is a conflicting AD domain.

• The script allows user to continue:

  Autodiscovery of servers for failover cannot work with this configuration.
  If you proceed with the installation, services will be configured to always access the discovered server for all operations and will not fail over to other servers in case of failure.
  Proceed with fixed values and no DNS discovery? [no]: yes

I think that we can handle that better:

• Detect AD and scream very loudly if AD is found instead of IPA
• Say more clearly that it is a bad idea to continue installation if auto-detection doesn't work
• Print information what ipa-client-install expected and didn't find (e.g. SRV records were not found etc.)