Simplify docker image creation workflow

.github/workflows/build-push-template.yml

@@ -10,40 +10,10 @@ jobs:
     if: ${{ github.repository == 'substrate-developer-hub/substrate-node-template' }}
     runs-on: ubuntu-18.04
     steps:
-    - uses: actions/checkout@v2
-
-    - name: Build and push the node-template Docker image
-      uses: docker/build-push-action@v1 # https://github.com/docker/build-push-action
-      with:
-        username: ${{ secrets.DOCKER_USERNAME }}
-        password: ${{ secrets.DOCKER_PASSWORD }}
-        dockerfile: .devcontainer/Dockerfile
-        repository: paritytech/substrate-playground-template-node-template
-        tags: latest
-        add_git_labels: true
-        tag_with_ref: true
-        tag_with_sha: true
-
-    - run: echo ::set-output name=image::paritytech/substrate-playground-template-node-template:sha-${GITHUB_SHA::7}
-      id: env
-
-    - name: Update devcontainer.json
-      run: |-
-        t=$(mktemp)
-        cat .devcontainer/devcontainer.json | jq ".image = \"${{ steps.env.outputs.image }}\"" > ${t} && mv ${t} .devcontainer/devcontainer.json
-
-    - name: Commit .devcontainer.json update
-      uses: EndBug/add-and-commit@v4
-      with:
-        message: ":bookmark: update image"
-        add: ".devcontainer/devcontainer.json"
-      env:
-        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-
     - name: Trigger playground inclusion
       uses: peter-evans/repository-dispatch@v1
       with:
         token: ${{ secrets.REPO_ACCESS_TOKEN }}
         repository: paritytech/substrate-playground
         event-type: template-updated
-        client-payload: '{"id": "node-template", "image": "${{ steps.env.outputs.image }}"}'
+        client-payload: '{"id": "node-template"}'