[Bug] RocketMQUtil.getResult leaks pending-future entries in the static response map on timeout/failure

### Describe the Bug

`RocketMQUtil.getResult` registers a `(msgId -> A2AResponseFuture)` entry in the static `MESSAGE_RESPONSE_MAP`, then blocks on `future.get(120, SECONDS)` and only removes the entry **after** `get` returns normally:

```java
msgIdAndAsyncTypedMap.put(responseMessageId, new A2AResponseFuture(completableFuture, typeReference));
String result = completableFuture.get(120, TimeUnit.SECONDS); // may throw
msgIdAndAsyncTypedMap.remove(responseMessageId); // skipped on any exception
return result;
```

`get` can throw `TimeoutException` (no reply within 120s), `ExecutionException` (failed reply), or `InterruptedException` — in all three cases the `remove` line is never reached. The completion side (`processNonStreamResult`) only calls `complete(...)` and never removes, and there is no periodic sweeper in the class, so the successful path of `getResult` is the only cleanup point.

Every timed-out or failed request therefore leaks one entry in a class-level static map for the lifetime of the JVM. Since tolerating slow/unavailable remote agents is exactly the scenario this transport exists for, the leak accumulates steadily and eventually OOMs a long-running process.

### Steps to Reproduce

Deterministic test (included in the incoming PR): register via a background `getResult`, then `completeExceptionally` the future — the entry stays in `MESSAGE_RESPONSE_MAP` on the unfixed code.

### What Did You Expect to See?

The pending entry is removed on every exit path of `getResult`.

### What Did You See Instead?

Entries leak on timeout/failure/interrupt and the static map grows without bound.

### Additional Context

Fix incoming: wrap the `get` in `try { ... } finally { msgIdAndAsyncTypedMap.remove(responseMessageId); }`. The streaming map (`MESSAGE_STREAM_RESPONSE_MAP`) may deserve the same audit as a follow-up.

Start at RocketMQUtil.getResult and inspect how entries are added to and removed from MESSAGE_RESPONSE_MAP around the timed future.get call. Reproduce the failure by completing the future exceptionally from a background getResult call; done means timeout, failure, and interruption paths all remove the pending entry, while the successful path still works.

Written by the indexing model from the issue text.