repo: gitea: workflows: dfi: impl: force remove dfi images

As a result of the `backup` action, images were not actually removed:

    "image is referenced in multiple repositories"

.gitea/workflows/dfi.bash

@@ -41,9 +41,9 @@ function host::clean()
     || echo "No docker-finance containers found"
 
   # Remove all images not in use
-  local -r _images=("$(docker images -aq)")
+  local -r _images=("$(docker images -a --format=table | grep docker-finance | gawk '{print $3}' | sort -u)")
   while read _line; do
-    docker image rm "$_line" || continue
+    docker image rm -f "$_line" || continue
   done < <(echo "${_images[@]}")
 
   # Remove all leftovers