Add --stack-only cli arg

--stack-only can also be used to disable the config-download workflow,
and has the same effect as --no-config-download, but with a better name.
The deprecation warning is removed as technically it's not deprecated to
deploy the Heat stack and not use the config-download workflow.

What is deprecated is using the
environments/disable-config-download-environment.yaml environment from
tripleo-heat-templates, and there is a deprecation warning in that file.

Change-Id: I78e9aa9cf4906e7b4e502f781a1ec0d94dfaebde

releasenotes/notes/config-download-default-to-true-1423abc46b294938.yaml

@@ -1,7 +1,5 @@
 ---
 features:
   - Using --config-download is now the default. A new CLI argument,
-    --no-config-download can be used to disable config-download, although that
-    method is deprecated.
-deprecations:
-  - Deploying without config-download (--no-config-download) is deprecated.
+    --no-config-download (or --stack-only) can be used to disable the
+    config-download workflow.

tripleoclient/v1/overcloud_deploy.py

@@ -791,12 +791,13 @@ class DeployOvercloud(command.Command):
         )
         parser.add_argument(
             '--no-config-download',
+            '--stack-only',
             action='store_false',
             default=False,
             dest='config_download',
-            help=_('Disable deployment via config-download mechanism. This '
-                   'method is DEPRECATED and the CLI arg and method may be '
-                   'removed in the future.')
+            help=_('Disable the config-download workflow and only create '
+                   'the stack and associated OpenStack resources. No '
+                   'software configuration will be applied.')
         )
         parser.add_argument(
             '--output-dir',
@@ -906,10 +907,6 @@ class DeployOvercloud(command.Command):
                                        parsed_args.overcloud_ssh_key,
                                        parsed_args.output_dir,
                                        verbosity=self.app_args.verbose_level)
-        else:
-            self.log.warning("Disabling config-download is DEPRECATED in "
-                             "Rocky. The ability to disable config-download "
-                             "may be removed in the future.")
 
         # Force fetching of attributes
         stack.get()