gha: ci-on-push: Depend on Commit Message Check

Let's make this workflow dependent of the commit message check, and only
start it if the commit message check one passes.

As a side effect, this allows us to run this specific workflow using
secrets, without having to rely on `pull_request_target`.

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

.github/workflows/ci-on-push.yaml

@@ -1,21 +1,19 @@
 name: Kata Containers CI
 on:
-  pull_request_target:
+  workflow_run:
+    workflows:
+      - Commit Message Check
     types:
-      - opened
-      - reopened
-      - labeled
-      - synchronize
+      - completed
 
 jobs:
   build-kata-static-tarball-amd64:
-    if: contains(github.event.pull_request.labels.*.name, 'ok-to-test')
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
     uses: ./.github/workflows/build-kata-static-tarball-amd64.yaml
     with:
       tarball-suffix: -${{ github.event.pull_request.number}}-${{ github.sha }}
 
   publish-kata-deploy-payload-amd64:
-    if: contains(github.event.pull_request.labels.*.name, 'ok-to-test')
     needs: build-kata-static-tarball-amd64
     uses: ./.github/workflows/publish-kata-deploy-payload-amd64.yaml
     with:
@@ -27,7 +25,6 @@ jobs:
     secrets: inherit
 
   run-k8s-tests-on-aks:
-    if: contains(github.event.pull_request.labels.*.name, 'ok-to-test')
     needs: publish-kata-deploy-payload-amd64
     uses: ./.github/workflows/run-k8s-tests-on-aks.yaml
     with: