ref(rules): Remove inner lock and add logging on exception (#70629)

Part of debugging the delayed rule processor lead here, we don't need
the inner lock (it's locked
[here](https://github.com/getsentry/sentry/blob/370e78ca10dddc2b018d1e9b6e41e501386cc0d2/src/sentry/buffer/redis.py#L316-L318)
before `process_batch` is called).

Author: ceorourke

src/sentry/buffer/redis.py

@@ -312,15 +312,10 @@ def get_hash(
         return decoded_hash
 
     def process_batch(self) -> None:
-        client = get_cluster_routing_client(self.cluster, self.is_redis_cluster)
-        lock_key = self._lock_key(client, self.pending_key, ex=10)
-        if not lock_key:
-            return
-
         try:
             redis_buffer_registry.callback(BufferHookEvent.FLUSH, self)
-        finally:
-            client.delete(lock_key)
+        except Exception:
+            logger.exception("process_batch.error")
 
     def incr(
         self,