Improve stage race condition by checking if staged before each try

[bvolpato]

A race condition can be easily introduced and exhaust all default withMaxRetries(4) with 2 job submissions / threads staging the same JAR at the same time, especially for large JARs:

2023-03-13 18:19:40 INFO TemplateTestBase:35 - 2023-03-13 18:19:40 WARN RetryHttpRequestInitializer:165 - Request failed with code 412, performed 0 retries due to IOExceptions, performed 0 retries due to unsuccessful status codes, HTTP framework says request can be retried, (caller responsible for retrying): https://storage.googleapis.com/upload/storage/v1/b/{bucket}/o?ifGenerationMatch=1678731567510887&name=2023-03-13-18-11_IT/staging/hbase-shaded-server-1.4.12-{hash}.jar&uploadType=resumable&upload_id={id}.

2023-03-13 18:19:40 INFO TemplateTestBase:35 - 2023-03-13 18:19:40 ERROR PackageUtil:191 - Upload failed, will NOT retry staging of package: /home/{user}/.m2/repository/org/apache/hbase/hbase-shaded-server/1.4.12/hbase-shaded-server-1.4.12.jar

2023-03-13 18:19:40 INFO TemplateTestBase:35 - java.io.IOException: Upload failed for 'gs://{bucket}/2023-03-13-18-11_IT/staging/hbase-shaded-server-1.4.12-{hash}.jar'

Even in scenarios in which a concurrent submission goes through, the artifacts are re-uploaded, making the cache useless under racing.

This change will check if the file was already staged before each try, instead of before entering the retry loop.

---

Thank you for your contribution! Follow this checklist to help us incorporate your contribution quickly and easily:

• Mention the appropriate issue in your description (for example: addresses #123), if applicable. This will automatically add a link to the pull request in the issue. If you would like the issue to automatically close on merging the pull request, comment fixes #<ISSUE NUMBER> instead.
• Update CHANGES.md with noteworthy changes.
• If this contribution is large, please file an Apache Individual Contributor License Agreement.

See the Contributor Guide for more tips on how to make review process smoother.

To check the build health, please visit https://github.com/apache/beam/blob/master/.test-infra/BUILD_STATUS.md

GitHub Actions Tests Status (on master branch)

See CI.md for more information about GitHub Actions CI.

[Abacn]

Looks like the failed unit tests are relevant?

org.apache.beam.runners.dataflow.util.PackageUtilTest.testPackageUploadEventuallySucceeds
org.apache.beam.runners.dataflow.util.PackageUtilTest.testPackageUploadFailsWhenIOExceptionThrown

[bvolpato]

Thanks @Abacn. Fixed it now. I had tested the functionality and didn't notice that test class.

Change was just around Mockito's verify as it now calls getObjects n times for n tries.

[Abacn]

Thanks, LGTM

just run './gradlew :runners:google-cloud-dataflow-java:spotlessApply' to fix code format

[bvolpato]

My bad, done -- feel free to merge.