chore: Correct memory acquired size in unified memory pool (apache#1738)

Although the `acquired` is always equal to the `additional` due to the current implicit semantics, it’s still better to make this logic explicit for clarity and better maintainability.

Author: zuston

native/core/src/execution/memory_pools/unified_pool.rs

@@ -115,7 +115,7 @@ impl MemoryPool for CometMemoryPool {
                     self.reserved()
                 ));
             }
-            self.used.fetch_add(additional, Relaxed);
+            self.used.fetch_add(acquired as usize, Relaxed);
         }
         Ok(())
     }