Improve build cleanup step to reduce failures (#24536)

.github/actions/setup/action.yml

@@ -11,15 +11,20 @@ outputs:
 runs:
   using: "composite"
   steps:
-    # Stop docker so we can mount more space at /var/lib/docker
+    # Prune preinstalled images, then stop docker so we can mount more space at
+    # /var/lib/docker
     - name: Stop docker
-      run: sudo systemctl stop docker
+      run: |
+        sudo docker image prune --all --force
+        sudo systemctl stop docker
       shell: bash
     # This creates a virtual volume at /var/lib/docker to maximize the size
     # As of 2/14/2024, this results in 97G for docker images
+    # Keep 4G on root for setup-qemu/buildx caches in ~/.docker and the tool cache
     - name: Maximize build space
       uses: easimon/maximize-build-space@master
       with:
+        root-reserve-mb: 4096
         remove-dotnet: 'true'
         remove-android: 'true'
         remove-haskell: 'true'