### What this PR does / why we need it?
Currently, when the MooncakeConnector interacts via ZeroMQ, it throws
the following exception upon send/receive failure:
**Issue 1:** The currently used `zmq.REQ` socket follows a strict
request-reply pattern, requiring an alternating sequence of send →
receive → send → receive... If either a send() or receive() operation
fails, the ZeroMQ socket becomes unusable.
**Solution:** When a send() or receive() exception occurs, close and
delete the ZeroMQ socket, and recreate it upon next use.
**Issue 2:** In `_handle_request`, if `_send_done_recv_signal` raises an
exception, the exception is thrown immediately and subsequent code is
not executed, causing the decode logic to fail to properly release the
request.
**Solution:** Move the call to `_send_done_recv_signal` to the end of
the function.
### Does this PR introduce _any_ user-facing change?
### How was this patch tested?
- vLLM version: v0.13.0
- vLLM main:
45c1ca1ca1
Signed-off-by: LCAIZJ <leichao139636@163.com>
d193316ded