fix: Use _send_action_server_request in send_action_for_execution

This ensures that all requests go through the proper error handling path,
including the 502 error handling that converts the error to a more helpful
AgentRuntimeDisconnectedError message.

Fixes #5601

Author: openhands-agent

openhands/runtime/impl/action_execution/action_execution_client.py

@@ -249,8 +249,7 @@ def send_action_for_execution(self, action: Action) -> Observation:
             assert action.timeout is not None
 
             try:
-                with send_request(
-                    self.session,
+                with self._send_action_server_request(
                     'POST',
                     f'{self._get_action_execution_server_host()}/execute_action',
                     json={'action': event_to_dict(action)},