[Bug] Proxy remoting expired request cleanup silently swallows exceptions

### Problem
`RemotingProtocolServer.cleanExpiredRequestInQueue` catches `Throwable` and ignores it while staying inside a `while (true)` cleanup loop. If queue inspection, task casting, or response cleanup repeatedly throws, the failure is invisible and the cleaner can keep looping without actionable diagnostics.

### Code evidence
- `proxy/src/main/java/org/apache/rocketmq/proxy/remoting/RemotingProtocolServer.java`: `cleanExpiredRequestInQueue` wraps the queue cleanup loop in `catch (Throwable ignored) {}`.

### Impact
Proxy operators lose the diagnostic signal for expired request cleanup failures. In the worst case, repeated exceptions can hide queue cleanup failure or cause avoidable loop churn, which works against Proxy Admin/runtime diagnostics and remoting observability.

### Expected behavior
The cleanup path should log a compact warning with queue context and stop the current cleanup pass after an unexpected exception, rather than swallowing the error silently.

### Scope
RocketMQ Studio track 2 / Proxy Admin runtime diagnostics and Proxy remoting observability.

Read proxy/src/main/java/org/apache/rocketmq/proxy/remoting/RemotingProtocolServer.java, focusing on cleanExpiredRequestInQueue and its cleanup loop. Verify the unexpected-exception path emits a compact warning with queue context and ends the current cleanup pass instead of silently continuing; run the relevant proxy/remoting tests if available.

Written by the indexing model from the issue text.