test: Fix TestGetKubeConfigPath unit test on windows

[bobsira]

Original failures were due to these mismatches:

• Windows treated "/home/fake/.kube/.kubeconfig:/home/fake2/.kubeconfig" as a single path (since : isn’t a list separator there), so the function returned the entire unsplit string, failing expectations.
• A lone ":" wasn’t recognized as “empty entries,” again because Windows expects ; as the separator.
• Default path comparison failed because the test expected a Unix-style $HOME/.kube/config while PathFromEnv() returned a native Windows path with backslashes.
• No normalization meant / vs \ differences caused equality failures.

By:

• Using os.PathListSeparator, multi-path input now splits correctly on all platforms.
• Normalizing separators and cleaning paths before comparing, platform-specific formatting differences no longer cause false negatives.
• Expanding $HOME after setting it (including fallback) guarantees consistent expected path construction.
• Leaving PathFromEnv() unchanged avoids breaking drive-letter semantics—splitting on : would corrupt paths.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: bobsira
Once this PR has been reviewed and has the lgtm label, please assign medyagh for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[k8s-ci-robot]

Hi @bobsira. Thanks for your PR.

I'm waiting for a github.com member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[minikube-bot]

Can one of the admins verify this patch?