Refactor integration tests infrastructure (#37462)

Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

.github/workflows/pull-docker-dryrun.yml

@@ -7,34 +7,33 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
   cancel-in-progress: true
 
+permissions:
+  contents: read
+
 jobs:
   files-changed:
     uses: ./.github/workflows/files-changed.yml
     permissions:
       contents: read
 
-  container:
+  # dryrun build is slow, so run them in parallel per-platform
+  container-amd64:
     if: needs.files-changed.outputs.docker == 'true'
-    needs: files-changed
-    runs-on: ubuntu-latest
-    permissions:
-      contents: read
-    steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-      - uses: docker/setup-qemu-action@ce360397dd3f832beb865e1373c09c0e9f86d70a # v4.0.0
-      - uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd # v4.0.0
-      - name: Build regular container image
-        uses: docker/build-push-action@bcafcacb16a39f128d818304e6c9c0c18556b85f # v7.1.0
-        with:
-          context: .
-          platforms: linux/amd64,linux/arm64,linux/riscv64
-          push: false
-          cache-from: type=registry,ref=ghcr.io/go-gitea/gitea:buildcache-rootful
-      - name: Build rootless container image
-        uses: docker/build-push-action@bcafcacb16a39f128d818304e6c9c0c18556b85f # v7.1.0
-        with:
-          context: .
-          push: false
-          platforms: linux/amd64,linux/arm64,linux/riscv64
-          file: Dockerfile.rootless
-          cache-from: type=registry,ref=ghcr.io/go-gitea/gitea:buildcache-rootless
+    needs: [files-changed]
+    uses: ./.github/workflows/part-docker-dryrun.yml
+    with:
+      platform: linux/amd64
+
+  container-arm64:
+    if: needs.files-changed.outputs.docker == 'true'
+    needs: [files-changed]
+    uses: ./.github/workflows/part-docker-dryrun.yml
+    with:
+      platform: linux/arm64
+
+  container-riscv64:
+    if: needs.files-changed.outputs.docker == 'true'
+    needs: [files-changed]
+    uses: ./.github/workflows/part-docker-dryrun.yml
+    with:
+      platform: linux/riscv64