Update build pipelines to support RC builds

.github/workflows/build_docker.yml

@@ -35,6 +35,8 @@ jobs:
       with:
         path: /tmp/.buildx-cache
         key: ${{ runner.os }}-buildx-${{ github.sha }}
+        restore-keys: |
+          ${{ runner.os }}-buildx-
 
     - name: Log in to GitHub Container Registry
       uses: docker/login-action@v3
@@ -43,16 +45,14 @@ jobs:
         username: ${{ github.actor }}
         password: ${{ secrets.GITHUB_TOKEN }}
 
-    # private image
     - name: Extract metadata (tags, labels) for Docker
-      if: ${{ !startsWith(github.ref, 'refs/tags/v') }}
       id: meta
       uses: docker/metadata-action@v5
       with:
-        images: ghcr.io/${{ github.repository }}
+        images: |
+          ghcr.io/${{ github.repository }}${{ github.ref.contains('-rc.') ? '' : '-testing' }}
 
     - name: Build and push Docker image
-      if: ${{ !startsWith(github.ref, 'refs/tags/v') }}
       uses: docker/build-push-action@v5
       with:
         context: .
@@ -66,27 +66,3 @@ jobs:
           BuiltAt=${{ steps.buildvars.outputs.built_at }}
           GitCommit=${{ steps.buildvars.outputs.git_commit }}
           Version=${{ steps.buildvars.outputs.version }}
-
-    # public image
-    - name: Extract metadata (tags, labels) for Docker
-      if: ${{ startsWith(github.ref, 'refs/tags/v') }}
-      id: publicmeta
-      uses: docker/metadata-action@v5
-      with:
-        images: ghcr.io/${{ github.repository }}-testing
-
-    - name: Build and push Docker image
-      if: ${{ startsWith(github.ref, 'refs/tags/v') }}
-      uses: docker/build-push-action@v5
-      with:
-        context: .
-        platforms: linux/amd64,linux/arm64,linux/arm/v7
-        push: true
-        tags: ${{ steps.publicmeta.outputs.tags }}
-        labels: ${{ steps.publicmeta.outputs.labels }}
-        cache-from: type=local,src=/tmp/.buildx-cache
-        cache-to: type=local,dest=/tmp/.buildx-cache
-        build-args: |
-          BuiltAt=${{ steps.buildvars.outputs.built_at }}
-          GitCommit=${{ steps.buildvars.outputs.git_commit }}
-          Version=${{ steps.buildvars.outputs.version }}