Build Java polyglot CLI E2E image via local docker daemon

The CLI E2E Java polyglot image extends the polyglot base via
`FROM aspire-e2e-polyglot-base`, which only exists in the local docker
daemon (it is loaded there via the `--load` option of the previous
buildx build). The docker-container buildx driver cannot see local
daemon images, so any attempt to build the Java image through the
shared `cli-e2e-builder` instance fails with `pull access denied for
docker.io/library/aspire-e2e-polyglot-base`.

Branch the `build_image` helper on the cache scope:
- non-empty scope  → cached buildx docker-container path
- empty scope      → daemon-driven `DOCKER_BUILDKIT=1 docker build`

Route the Java image through `build_with_mirror_retry` with an empty
cache scope so it picks the daemon-driven path and the special-case
`build_java_image` helper can be removed. Behavior matches what
docs/ci/cli-e2e-images.md already calls out: the Java image is built
from the local polyglot base and does not use a shared BuildKit cache
scope.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: radical

.github/workflows/build-cli-e2e-image.yml

@@ -75,32 +75,29 @@ jobs:
               echo "Building $display_name with the default Ubuntu apt sources"
             fi
 
-            docker buildx build \
-              --load \
-              --cache-from "type=gha,scope=$cache_scope" \
-              --cache-to "type=gha,scope=$cache_scope,mode=max,ignore-error=true" \
-              "${build_args[@]}" \
-              -f "$dockerfile" \
-              -t "$tag" \
-              .
-          }
-
-          build_java_image() {
-            local mirror="$1"
-            local -a build_args=()
-
-            if [[ -n "$mirror" ]]; then
-              echo "Building Java polyglot image with Ubuntu apt mirror: $mirror"
-              build_args+=(--build-arg "UBUNTU_APT_MIRROR=$mirror")
+            if [[ -n "$cache_scope" ]]; then
+              # Cached path: use the buildx docker-container builder so we can read/write
+              # BuildKit layers from the GitHub Actions cache.
+              docker buildx build \
+                --load \
+                --cache-from "type=gha,scope=$cache_scope" \
+                --cache-to "type=gha,scope=$cache_scope,mode=max,ignore-error=true" \
+                "${build_args[@]}" \
+                -f "$dockerfile" \
+                -t "$tag" \
+                .
             else
-              echo "Building Java polyglot image with the default Ubuntu apt sources"
+              # Uncached path: build through the default docker daemon driver so the
+              # image can reference other locally-loaded images via FROM (e.g. the
+              # polyglot base built earlier in this step). The docker-container buildx
+              # driver does not have access to the daemon's image store and would try
+              # to pull such references from a registry.
+              DOCKER_BUILDKIT=1 docker build \
+                "${build_args[@]}" \
+                -f "$dockerfile" \
+                -t "$tag" \
+                .
             fi
-
-            DOCKER_BUILDKIT=1 docker build \
-              "${build_args[@]}" \
-              -f tests/Shared/Docker/Dockerfile.e2e-polyglot-java \
-              -t "$CLI_E2E_POLYGLOT_JAVA_IMAGE_TAG" \
-              .
           }
 
           build_with_mirror_retry() {
@@ -121,10 +118,11 @@ jobs:
             build_with_mirror_retry "polyglot base image" "tests/Shared/Docker/Dockerfile.e2e-polyglot-base" "$CLI_E2E_POLYGLOT_BASE_IMAGE_TAG" "$CLI_E2E_POLYGLOT_BASE_IMAGE_CACHE_SCOPE"
             docker tag "$CLI_E2E_POLYGLOT_BASE_IMAGE_TAG" "$CLI_E2E_POLYGLOT_IMAGE_TAG"
 
-            if ! build_java_image "http://azure.archive.ubuntu.com/ubuntu/"; then
-              echo "Java polyglot image build failed with the Azure Ubuntu apt mirror; retrying with default Ubuntu apt sources"
-              build_java_image ""
-            fi
+            # The Java polyglot image extends the polyglot base via `FROM
+            # aspire-e2e-polyglot-base`, which only exists in the local docker daemon.
+            # Pass an empty cache scope so build_image uses the daemon-backed
+            # `docker build` path instead of the docker-container buildx driver.
+            build_with_mirror_retry "Java polyglot image" "tests/Shared/Docker/Dockerfile.e2e-polyglot-java" "$CLI_E2E_POLYGLOT_JAVA_IMAGE_TAG" ""
           fi
 
       - name: Save CLI E2E Docker image tarballs