HDDS-14346. Reduce duplication in multipart upload unit tests

[adoroszlai]

What changes were proposed in this pull request?

• Reduce duplication in S3 Gateway unit tests related to multipart uploads.
  • Extract new utilities to initiate MPU, upload part and complete MPU.
  • Merge TestPartUploadWithStream into TestPartUpload and parameterize.
  • Merge testPartUpload and testPartUploadWithOverride.
  • Move assertion about content length to testPartUpload, delete testPartUploadContentLength.
• Reuse EndpointTestUtils#put and other helpers in TestObjectGet and TestUploadWithStream. Now ObjectEndpoint#put is used only via EndpointTestUtils.

This is a test-only change.

https://issues.apache.org/jira/browse/HDDS-14346

How was this patch tested?

Build, checkstyle, unit tests.

https://github.com/adoroszlai/ozone/actions/runs/20718234501

[swamirishi]

@rnblough Do you wanna take a look at this patch?

[ivandika3]

@adoroszlai Thanks for the patch. LGTM +1.

[peterxcli]

LGTM +1

[peterxcli]

Thanks @adoroszlai for the patch, @ivandika3 for the review.

[adoroszlai]

Thanks @ivandika3, @peterxcli for the review.