Use 'build' environment for Docker building and test login on pull-requests (#1539)

* Use 'build' environment for Docker building

* Test login on pull-requests too

Author: leplatrem

.github/workflows/build-publish.yaml

@@ -23,6 +23,7 @@ jobs:
       GAR_REPOSITORY: telescope-prod
       GCP_PROJECT_ID: moz-fx-telescope-prod
       IMAGE: telescope
+    environment: build
     steps:
       - name: Check out the repo
         uses: actions/checkout@v4
@@ -56,29 +57,26 @@ jobs:
           tags: |
             type=raw,value=latest
             type=raw,value=${{ steps.determine_tag.outputs.TAG }}
-      
+
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
-      - id: gcp_auth
-        name: gcp auth
-        if: github.event_name != 'pull_request'
+      - name: GCP Auth
+        id: gcp_auth
         uses: google-github-actions/auth@v2
         with:
           token_format: access_token
           service_account: artifact-writer@${{ env.GCP_PROJECT_ID }}.iam.gserviceaccount.com
           workload_identity_provider: ${{ vars.GCPV2_GITHUB_WORKLOAD_IDENTITY_PROVIDER }}
 
       - name: Login to GAR
-        if: github.event_name != 'pull_request'
         uses: docker/login-action@v3
         with:
           registry: ${{ env.GAR_LOCATION }}-docker.pkg.dev
           username: oauth2accesstoken
           password: ${{ steps.gcp_auth.outputs.access_token }}
 
       - name: Login to Docker Hub
-        if: github.event_name != 'pull_request'
         uses: docker/login-action@v3
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}