HDDS-16025. Allow old clients to start finalization on a new server.

[errose28]

What changes were proposed in this pull request?

An old client's finalize upgrade command to OM should still start the finalization process. The server will need to return a different response to the old client and redirect to the new finalization flow internally. This has already been handled on SCM in HDDS-15609.

• Create a common base class to handle overlapping logic of the new and old request types in OM
  • Add a subclass for the new and old request types to handle their unique concerns.
  • Note that this does not require compatibility handling among the OMs because we must upgrade to this version before we can do ZDU with mixed OM versions.
• Previously the old finalize request type had been repurposed for internal finalization among OMs, creating a compatibility issue when older clients sent that type.
  • This request type is now exclusively for old clients to trigger finalization, and the new internal OM finalize request has a dedicated request type.
• Remove unused method org.apache.hadoop.hdds.scm.client.ScmClient#finalizeUpgrade left over from an earlier implementation on the feature branch where finalization started from client to SCM.

The high line count is due to the new integration test and movement of existing code in the finalize requests. Most changes do not introduce new functionality.

What is the link to the Apache JIRA

HDDS-16025

How was this patch tested?

• Unit tests for request/response types added.
• Integration test added to test full cluster finalization with the old finalize and status RPCs.

[sodonnel]

I believe this looks good. As stated in the description much of the new line count is due to tests and lifting some existing code into a new shared base class, so the change isn't as large as it first appears.

[errose28]

Unfortunately this broke something at the acceptance level that I need to figure out: https://github.com/errose28/ozone/actions/runs/32425781316/job/96617583956