Ensure we're using the stackname for the inventory

Until now, the inventory path used by the overcloud_delete.py was wrong,
since it wasn't using the "stackname", leading to a wrong
/home/stack/config-download/{}/tripleo-ansible-inventory.yaml path.

While it's not a big issue with non-TLS-e deploy, it becomes an actual
problem when we involve FreeIPA and TLS-e, since the deletion won't
remove the nodes nor services from FreeIPA.

Closes-Bug: #1950155

Change-Id: I5941bf9948c5f17e7406d34c21b8de9bd174c063
(cherry picked from commit 9fd913f57c)

tripleoclient/tests/v2/overcloud_delete/test_overcloud_delete.py

@@ -47,7 +47,7 @@ class TestDeleteOvercloud(deploy_fakes.TestDeployOvercloud):
 
         mock_run_playbook.assert_called_once_with(
             ['cli-cleanup-ipa.yml', 'cli-overcloud-delete.yaml'],
-            constants.ANSIBLE_INVENTORY,
+            constants.ANSIBLE_INVENTORY.format('overcast'),
             mock.ANY,
             constants.ANSIBLE_TRIPLEO_PLAYBOOKS,
             extra_vars={
@@ -82,7 +82,7 @@ class TestDeleteOvercloud(deploy_fakes.TestDeployOvercloud):
                 'cli-overcloud-node-unprovision.yaml',
                 'localhost,',
                 mock.ANY,
-                constants.ANSIBLE_TRIPLEO_PLAYBOOKS,
+                constants.ANSIBLE_TRIPLEO_PLAYBOOKS.format('overcast'),
                 extra_vars={
                     "stack_name": "overcast",
                     "baremetal_deployment": mock.ANY,
@@ -152,7 +152,7 @@ class TestDeleteOvercloud(deploy_fakes.TestDeployOvercloud):
 
         mock_run_playbook.assert_called_once_with(
             ['cli-overcloud-delete.yaml'],
-            constants.ANSIBLE_INVENTORY,
+            constants.ANSIBLE_INVENTORY.format('overcast'),
             mock.ANY,
             constants.ANSIBLE_TRIPLEO_PLAYBOOKS,
             extra_vars={

tripleoclient/v2/overcloud_delete.py

@@ -115,7 +115,7 @@ class DeleteOvercloud(command.Command):
         with utils.TempDirs() as tmp:
             utils.run_ansible_playbook(
                 playbooks,
-                constants.ANSIBLE_INVENTORY,
+                constants.ANSIBLE_INVENTORY.format(parsed_args.stack),
                 workdir=tmp,
                 playbook_dir=constants.ANSIBLE_TRIPLEO_PLAYBOOKS,
                 verbosity=utils.playbook_verbosity(self=self),