Cleanup yaml formatting (#5151)

* Add yamllint config.
* Add yamllint workflow.
* Cleanup linting issues.
* Remove unnecessary `set -x -e` from workflows.

Signed-off-by: SuperQ <superq@gmail.com>

.github/workflows/yamllint.yml

@@ -0,0 +1,18 @@
+name: 'Yamllint GitHub Actions'
+on:
+  - pull_request
+jobs:
+  yamllint:
+    name: 'Yamllint'
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Checkout'
+        uses: actions/checkout@master
+      - name: 'Yamllint'
+        uses: karancode/yamllint-github-action@master
+        with:
+          yamllint_file_or_dir: '.'
+          yamllint_strict: false
+          yamllint_comment: true
+        env:
+          GITHUB_ACCESS_TOKEN: ${{ secrets.GITHUB_TOKEN }}