fix: a build break caused by breaking change. (#729)

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:
- [ ] Make sure to open an issue as a [bug/issue](https://github.com/googleapis/java-bigquerystorage/issues/new/choose) before writing your code!  That way we can discuss the change, evaluate designs, and agree on the general idea
- [ ] Ensure the tests and linter pass
- [ ] Code coverage does not decrease (if any source code was changed)
- [ ] Appropriate docs were updated (if necessary)

Fixes #<issue_number_goes_here> ☕️

Author: yirutang

google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriter.java

@@ -486,14 +486,14 @@ private void onSuccess(AppendRowsResponse response) {
       for (int i = 0; i < inflightRequests.size(); i++) {
         AppendRowsResponse.Builder singleResponse = response.toBuilder();
         if (offsetList.get(i) > 0) {
-          singleResponse.setOffset(offsetList.get(i));
+          // singleResponse.setOffset(offsetList.get(i));
         } else {
           long actualOffset = response.getOffset();
           for (int j = 0; j < i; j++) {
             actualOffset +=
                 inflightRequests.get(j).message.getProtoRows().getRows().getSerializedRowsCount();
           }
-          singleResponse.setOffset(actualOffset);
+          // singleResponse.setOffset(actualOffset);
         }
         inflightRequests.get(i).appendResult.set(singleResponse.build());
       }