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/whitespace.yml

@@ -8,23 +8,22 @@ jobs:
   fix:
     runs-on: ubuntu-latest
     steps:
-      -
-        name: Checkout
+      - name: Checkout
         uses: actions/checkout@v2
-      -
-        name: Remove Trailing Whitespaces
+
+      - name: Remove Trailing Whitespaces
         run: |
           find . -not -path '*/\.git/*' -type f -not -name '*.go' -exec sed -i 's/[[:space:]]\{1,\}$//' {} \+
-      -
-        name: Set up Git
+
+      - name: Set up Git
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           git config user.name "coredns[bot]"
           git config user.email "bot@bot.coredns.io"
           git remote set-url origin https://x-access-token:${GITHUB_TOKEN}@github.com/${GITHUB_REPOSITORY}.git
-      -
-        name: Commit and push changes
+
+      - name: Commit and push changes
         run: |
           git add .
           if output=$(git status --porcelain) && [ ! -z "$output" ]; then