improve latency when a client is unblocked by module timer (#9593)

Scenario:
1. client block on command `XREAD BLOCK 0 STREAMS mystream  $`
2. in a module, calling `XADD mystream * field value` via lua from a timer callback
3. client will receive response after some latency up to 100ms

Reason:
When `XADD` signal the key `mystream` as ready, `beforeSleep` in next eventloop will call
`handleClientsBlockedOnKeys` to unblock the client and add pending data to write but not
actually install a write handler, so next redis will block in `aeApiPoll` up to 100ms given `hz`
config as default 10, pending data will be sent in another next eventloop by
`handleClientsWithPendingWritesUsingThreads`.

Calling `handleClientsBlockedOnKeys` before `handleClientsWithPendingWritesUsingThreads`
in `beforeSleep` solves the problem.

src/server.c

@@ -2941,17 +2941,17 @@ void beforeSleep(struct aeEventLoop *eventLoop) {
     if (server.aof_state == AOF_ON)
         flushAppendOnlyFile(0);
 
+    /* Try to process blocked clients every once in while. Example: A module
+     * calls RM_SignalKeyAsReady from within a timer callback (So we don't
+     * visit processCommand() at all). */
+    handleClientsBlockedOnKeys();
+
     /* Handle writes with pending output buffers. */
     handleClientsWithPendingWritesUsingThreads();
 
     /* Close clients that need to be closed asynchronous */
     freeClientsInAsyncFreeQueue();
 
-    /* Try to process blocked clients every once in while. Example: A module
-     * calls RM_SignalKeyAsReady from within a timer callback (So we don't
-     * visit processCommand() at all). */
-    handleClientsBlockedOnKeys();
-
     /* Disconnect some clients if they are consuming too much memory. */
     evictClients();