ipa-client-install: autodiscovery must refuse single-label domains
Since commit 905ab93, ipa-server-install refuses single-label domains,
but older IPA server versions could be installed with a single-label
domain/realm.
ipa-client-install is already refusing single-label domain/realm when
provided to the CLI with --domain / --realm but does not perform the same
check when the domain is discovered.
This commit adds a check to domain names automatically discovered and skips
single-label domains. Same check for realm names.
Fixes: https://pagure.io/freeipa/issue/7598
Reviewed-By: Rob Crittenden <rcritten@redhat.com>