chore(CI): remove setup-QEMU from docker-test (#9690)

useless step

Signed-off-by: Rongrong <i@rong.moe>

.github/workflows/docker-test.yml

@@ -25,10 +25,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v3
 
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v1
-
-      - name: Set up Docker Buildx
+      - name: Set up Docker Buildx  # needed by `cache-from`
         uses: docker/setup-buildx-action@v1
 
       - name: Extract Docker metadata