Disable "chunked" uploading by the GCS client for objects smaller than the chunk size. (#5835)

By disabling chunked uploading when the object size is less than the chunk size,
memory is not allocated unnecessarily.

cmd/gateway/gcs/gateway-gcs.go

@@ -839,6 +839,11 @@ func (l *gcsGateway) PutObject(ctx context.Context, bucket string, key string, d
 	object := l.client.Bucket(bucket).Object(key)
 
 	w := object.NewWriter(l.ctx)
+	// Disable "chunked" uploading in GCS client if the size of the data to be uploaded is below
+	// the current chunk-size of the writer. This avoids an unnecessary memory allocation.
+	if data.Size() < int64(w.ChunkSize) {
+		w.ChunkSize = 0
+	}
 	applyMetadataToGCSAttrs(metadata, &w.ObjectAttrs)
 
 	if _, err := io.Copy(w, data); err != nil {