Replace exception with LOG.info

Updated _run_validator_run to no longer raise an execption if/when a group is empty

Using a log vs. exception is useful when we want to run an automated set of validations
within our Update CI pipeline.

Co-authored-by: Daniel Bengtsson <dbengt@redhat.com>
Change-Id: I1046148da87712934184373a10fa3d2a46e620e4

tripleo_validations/tripleo_validator.py

@@ -420,7 +420,7 @@ class TripleOValidatorRun(command.Command):
             print(t)
         else:
             msg = "No Validation has been run, please check your parameters."
-            raise exceptions.CommandError(msg)
+            LOG.info(_(msg))
 
         if not parsed_args.static_inventory:
             LOG.debug(_('Removing static tripleo ansible inventory file'))