Fix memory leaking when loading data

### What changes are proposed in this pull request?

Release buffer when an exception occurs.

### Why are the changes needed?
Fix memory leaking.

			pr-link: #17758
			change-id: cid-b5e9e655aff744b04d3187687a62dbaed6754186

core/server/worker/src/main/java/alluxio/worker/block/MonoBlockStore.java

@@ -343,12 +343,12 @@ public CompletableFuture<List<BlockStatus>> load(List<Block> blocks, UfsReadOpti
               blockWriter.close();
             } catch (IOException e) {
               throw AlluxioRuntimeException.from(e);
-            } finally {
-              NioDirectBufferPool.release(buf);
             }
           })
           .thenRun(() -> commitBlock(sessionId, blockId, false))
+          .thenRun(() -> NioDirectBufferPool.release(buf))
           .exceptionally(t -> {
+            NioDirectBufferPool.release(buf);
             handleException(t.getCause(), block, errors, sessionId);
             return null;
           });