Second part of the fix for bug#53499. We decrement the active thread count

when the purge thread completes by calling srv_suspend_thread().

storage/innobase/srv/srv0srv.c

@@ -3236,6 +3236,9 @@ srv_purge_thread(
 		srv_sync_log_buffer_in_background();
 	}
 
+	/* Decrement the active count. */
+	srv_suspend_thread();
+
 	/* Free the thread local memory. */
 	thr_local_free(os_thread_get_curr_id());