Test: there are cross-interference between test cases in `cell_klist_test` suite

[kirk0830]

Describe the Testing Issue

see draft PR #3855, the addition of unittests on newly implemented functions should not cause crashes of old unittests, present failure might result from sharing of one K_Vectors instance by all unittest cases.

Additional Context

No response

Task list for Issue attackers (only for developers)

• [ ] Understand the testing issue described by the developer.
• [ ] Review the specific test case, expected and actual results, and any error messages.
• [ ] Identify the root cause of the test failure or issue.
• [ ] If a possible solution is suggested, evaluate its feasibility and effectiveness.
• [ ] Implement a fix for the test failure or issue, or create a new test case if needed.
• [ ] Verify that the fix resolves the testing issue and the test case passes.
• [ ] Review and update any relevant documentation, such as test plans or user guides.
• [ ] Ensure the testing issue is resolved and close the ticket.
• [ ] Share any lessons learned or best practices with the team to prevent similar issues in the future.