fix(listVolume): only set nextToken if not empty

[guilhem]

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]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 73.01%. Comparing base (685e341) to head (eb40379).
Report is 21 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/driver/controllerserver.go	0.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #391      +/-   ##
==========================================
- Coverage   73.11%   73.01%   -0.10%     
==========================================
  Files          23       23              
  Lines        2648     2650       +2     
==========================================
- Hits         1936     1935       -1     
- Misses        585      587       +2     
- Partials      127      128       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.