Extend cleanup CLI to delete regions

RegionService class enables deletion of regions which were
neglected by tempest cleanup before.

Change-Id: I2c978a7b2151b37bb0a224bafd1be490f04950ee
Closes-Bug: #1848672
diff --git a/releasenotes/notes/Extend-cleanup-CLI-to-delete-regions-9f1dbda2c8de12e2.yaml b/releasenotes/notes/Extend-cleanup-CLI-to-delete-regions-9f1dbda2c8de12e2.yaml
new file mode 100644
index 0000000..e2fc5b3
--- /dev/null
+++ b/releasenotes/notes/Extend-cleanup-CLI-to-delete-regions-9f1dbda2c8de12e2.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    tempest cleanup CLI is extended about region deletion. Until now, the
+    regions have been neglected by tempest cleanup. From now on, tempest
+    cleanup is able to delete leftover regions as well.