HDDS-7211. remove dead code from org.apache.hadoop.ozone.omKeyManagerImpl

[myskov]

What changes were proposed in this pull request?

This PR removes dead code from omKeyManagerImpl class. The most significant part of the removed code is helper methods of listStatusFSO(), which is unreachable and has been removed.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-7211

How was this patch tested?

Existing unit and integration tests

[kerneltime]

@neils-dev

[kerneltime]

I think there needs to be a couple of more reviewers to approve this PR, there is a lot of code that is being deleted (which is good) but we need to be sure that it won't be missed.

[aswinshakil]

Thank you for working on this @myskov. I remember there was a plan to do a cleanup patch of listStatusFSO() after this patch but wasn't done. I can approve it once the merge conflicts are resolved.

[myskov]

@aswinshakil I resolved all conflicts.

[myskov]

since @aswinshakil hasn't been active for the last week, could you take a look at the PR please @kerneltime@adoroszlai ?

[adoroszlai]

Thanks @myskov for the cleanup, LGTM. We can wait for @aswinshakil to take another look before merging this.

[aswinshakil]

Thanks for the cleanup @myskov. Approved it. For future reference, Please avoid force pushing as it makes it harder to review incremental changes.

[adoroszlai]

Thanks @myskov for the patch, @aswinshakil, @kerneltime for the review.