rhsm_repository: Properly handle no repos (#51938)

When no repos are defined, the `repo` variable is undefined. Therefore
append it only to the result if a repo was found. Otherwise Ansible will
fail with an UnboundLocalError.

changelogs/fragments/rhsm_repository-handle-no-repos.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - rhsm_repository - handle systems without any repos

lib/ansible/modules/packaging/os/rhsm_repository.py

@@ -160,7 +160,7 @@ def get_repository_list(module, list_parameter):
                 "enabled": True if repo_enabled == '1' else False
             }
 
-        repo_result.append(repo)
+            repo_result.append(repo)
 
     return repo_result