fix(k8s): handle Kubernetes kubeconfig content correctly

[MrCloudSec]

Description

• Ensured the SDK uses consistent Kubernetes credentials regardless of whether the kubeconfig is provided as a multi-line string or a file.

Checklist

• Are there new checks included in this PR? Yes / No
  • If so, do we need to update permissions for the provider? Please review this carefully.
• Review if the code is being covered by tests.
• Review if code is being documented following this specification https://github.com/google/styleguide/blob/gh-pages/pyguide.md#38-comments-and-docstrings
• Review if backport is needed.

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Attention: Patch coverage is 88.23529% with 2 lines in your changes missing coverage. Please review.

Project coverage is 89.92%. Comparing base (bcf1ef1) to head (49446a7).
Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
...rowler/providers/kubernetes/kubernetes_provider.py	88.23%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5939      +/-   ##
==========================================
- Coverage   89.93%   89.92%   -0.02%     
==========================================
  Files        1147     1147              
  Lines       35599    35608       +9     
==========================================
+ Hits        32017    32020       +3     
- Misses       3582     3588       +6     

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

[paabloLC]

Please check my comment on the CustomInput component.

[jfagoagas]

Great fix @MrCloudSec 👏

UI changes are not needed at the end.

[prowler-bot]

💚 All backports created successfully

Status	Branch	Result
✅	v4.6

Questions ?

Please refer to the Backport tool documentation and see the Github Action logs for details