remove --oldinstallonly: when no old installonly packages, exit with 0

If no old installonly packages are present, then the command succesfully
removed all of them and should exit with 0 and write the message to
stdout instead of stderr.

dnf/cli/commands/remove.py

@@ -124,8 +124,7 @@ def run(self):
  for pkg in instonly:
  self.base.package_remove(pkg)
  else:
- raise dnf.exceptions.Error(
- _('No old installonly packages found for removal.'))
+ logger.info(_('No old installonly packages found for removal.'))
  return
 
  # Remove groups.