[Clean-Up] Refactor NodeUnpublishVolume()

[komer3]

General:

• [ ] Have you removed all sensitive information, including but not limited to access keys and passwords?
• [ ] Have you checked to ensure there aren't other open or closed Pull Requests for the same bug/feature/question?

Pull Request Guidelines:

1. [ ] Does your submission pass tests?
2. [ ] Have you added tests?
3. [ ] Are you addressing a single feature in this PR?
4. [ ] Are your commits atomic, addressing one change per commit?
5. [ ] Are you following the conventions of the language?
6. [ ] Have you saved your large formatting changes for a different PR, so we can focus on your work?
7. [ ] Have you explained your rationale for why this feature is needed?
8. [ ] Have you linked your PR to an open issue

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 46.15385% with 7 lines in your changes missing coverage. Please review.

Project coverage is 36.69%. Comparing base (a917258) to head (95cba46). Report is 4 commits behind head on main.

Files	Patch %	Lines
internal/driver/nodeserver.go	0.00%	7 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #200 +/- ## ========================================== + Coverage 36.38% 36.69% +0.30% ========================================== Files 22 22 Lines 1594 1597 +3 ========================================== + Hits 580 586 +6 + Misses 980 977 -3 Partials 34 34 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.