ci(pipeline): streamline container registry configuration

- Replaced separate Docker Hub and GitHub Container Registry entries with a unified container image registry variable.
- Removed redundant Docker Hub login steps to simplify the CI pipeline.
- Updated helm push commands to utilize the new registry variable for consistency.

Author: winromulus

.github/workflows/pipeline.yaml

@@ -28,8 +28,7 @@ env:
   containerImage: "kubernetes-reflector"
   containerImageBuildContext: "src/"
   containerImageBuildDockerfile: "src/ES.Kubernetes.Reflector/Dockerfile"
-  dockerHubContainerImageRepository: "emberstack"
-  ghcrContainerImageRepository: "ghcr.io/emberstack"
+  containerImageRegistry: "ghcr.io/emberstack"
   helmChart: "reflector"
   helmChartDir: "src/helm/reflector"
 
@@ -135,11 +134,6 @@ jobs:
         run: |
           echo "${{ secrets.ES_GITHUB_PAT }}" | helm registry login ghcr.io -u ${{ github.actor }} --password-stdin
 
-      - name: tools - helm - login - docker.io
-        if: ${{ needs.discovery.outputs.requiresBuildPush == 'true' }}
-        run: |
-          echo "${{ secrets.ES_DOCKERHUB_PAT }}" | helm registry login registry-1.docker.io -u ${{ secrets.ES_DOCKERHUB_USERNAME }} --password-stdin
-
       - name: tools - docker - login ghcr.io
         if: ${{ needs.discovery.outputs.requiresBuildPush == 'true' }}
         uses: docker/login-action@v3
@@ -148,14 +142,6 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.ES_GITHUB_PAT }}
 
-      - name: tools - docker - login docker.io
-        if: ${{ needs.discovery.outputs.requiresBuildPush == 'true' }}
-        uses: docker/login-action@v3
-        with:
-          registry: docker.io
-          username: ${{ secrets.ES_DOCKERHUB_USERNAME }}
-          password: ${{ secrets.ES_DOCKERHUB_PAT }}
-
       - name: tools - docker - register QEMU
         run: |
           docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
@@ -165,7 +151,6 @@ jobs:
         with:
           driver: docker-container  # REQUIRED for multi-platform builds
 
-
       - name: artifacts - prepare directories
         run: |
           mkdir -p .artifacts/helm
@@ -189,16 +174,11 @@ jobs:
           provenance: false
           platforms: linux/amd64,linux/arm/v7,linux/arm64
           tags: |
-            ${{ env.dockerHubContainerImageRepository }}/${{ env.containerImage }}:${{ env.gitVersion_SemVer }}
-            ${{ env.ghcrContainerImageRepository }}/${{ env.containerImage }}:${{ env.gitVersion_SemVer }}
+            ${{ env.containerImageRegistry }}/${{ env.containerImage }}:${{ env.gitVersion_SemVer }}
 
-      - name: helm - push - ghcr
+      - name: helm - push - ghcr.io
         run: helm push .artifacts/helm/${{ env.helmChart }}-${{ env.gitVersion_SemVer }}.tgz oci://ghcr.io/${{ github.repository_owner }}/helm-charts
 
-      - name: helm - push - docker.io
-        run: helm push .artifacts/helm/${{ env.helmChart }}-${{ env.gitVersion_SemVer }}.tgz oci://registry-1.docker.io/${{ github.repository_owner }}/helm-charts
-
-
       - name: "artifacts - upload - helm chart"
         uses: actions/upload-artifact@v4
         with: