Go: Add admin server status checking (#13571)

### What problem does this PR solve?

RAGFlow server isn't available when admin server isn't connected.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

docker/entrypoint.sh

@@ -249,6 +249,7 @@ if [[ "${ENABLE_ADMIN_SERVER}" -eq 1 ]]; then
     echo "Starting admin_server..."
     while true; do
         "$PY" admin/server/admin_server.py &
+        bin/admin_server &
         wait;
         sleep 1;
     done &