feat: 로깅 추가

src/main/java/com/woowacamp/storage/domain/file/service/FileWriterThreadPool.java

@@ -65,6 +65,7 @@ public void produce(InitiateMultipartUploadResult initResponse, String currentFi
 			throw ErrorCode.FILE_UPLOAD_FAILED.baseException();
 		}
 		log.info("current thread count: {}", ((ThreadPoolExecutor)executorService).getActiveCount());
+		log.info("current queue size: {}", ((ThreadPoolExecutor)executorService).getQueue().size());
 		executorService.execute(() -> {
 			log.info("currentThread: {}, partNumber: {}", Thread.currentThread().getId(), partNumber);
 			uploadPart(initResponse.getUploadId(), currentFileName, partNumber, contentBuffer, bufferLength, partETags);