HBASE-30319 Remove unused private fields flagged by new UnusedPrivateFie…

[ZaheerAhmadDev]

Description:

Removes a couple of unused private fields identified while testing a new checkstyle check UnusedPrivateFieldCheck, currently in review upstream in the (checkstyle/checkstyle#19816) project.

Diff report of hbase : Found violations in diff report : https://checkstyle-diff-reports.s3.us-east-2.amazonaws.com/31a666b_2026091037/reports/diff/Hbase/index.html

What the check does:
it flags private fields that are declared but never referenced anywhere in the file a common source of dead code in large, long-lived codebases. It's aware of common false-positive sources (reflection-based frameworks, Lombok, DI annotations, etc. via a configurable ignoreAnnotationCanonicalNames property) and ignores well-known name-based conventions like serialVersionUID by default via ignoredFieldNames or user can customize for their own use case .

Each was manually verified as genuinely unused before removal not referenced via reflection, annotations, or any other indirect means.

This is primarily meant as real-world signal for the check development feedback on false positives, edge cases, or naming conventions this project relies on is very welcome, and will help shape the check before it's finalized upstream.

Issue: HBASE-30319

[Apache9]

Thanks for putting up this PR.

HBase uses jira for tracking issues. So please follow the guideline in the README.md for contributing.

[ZaheerAhmadDev]

Thanks for putting up this PR.

HBase uses jira for tracking issues. So please follow the guideline in the README.md for contributing.

@Apache9
Thanks,
Updated the title to reference HBASE-30319, please review it when you get a chance.