Case RE-851: Only run OpenStack GitHub Action when TestSuite Completes

Changelog:

.github/workflows/openstack.yml

@@ -9,6 +9,11 @@ on:
       - "*"
   pull_request:
   workflow_dispatch:
+  workflow_run:
+    workflow: [testsuite]
+    branches: [main]
+    types:
+      - completed
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
@@ -559,4 +564,4 @@ jobs:
           name: ${{ github.run_id }}-tf.out.json
           path: ${{ github.workspace }}/tf.out.json
       - name: Destroy OpenStack VM
-        run: terraform destroy -no-color -auto-approve 
+        run: terraform destroy -no-color -auto-approve