Simplify Docker release workflow by removing submodule checkout

Removed submodule checkout step from Docker release workflow.

.github/workflows/docker-release.yml

@@ -73,21 +73,6 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
-        with:
-          submodules: false
-
-      - name: Checkout submodules (retry)
-        run: |
-          set -euo pipefail
-          git submodule sync --recursive
-          for attempt in 1 2 3 4 5; do
-            if git -c protocol.version=2 submodule update --init --force --depth=1 --recursive; then
-              exit 0
-            fi
-            echo "Submodule update failed (attempt $attempt/5). Retrying…"
-            sleep $((attempt * 10))
-          done
-          exit 1
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3