Overwriting env vars again

[Stasmo]

Describe the bug
Basically issue 954 again

You're referencing process.env and then overwriting the values in it.

https://github.com/kubernetes-client/javascript/blob/main/src/exec_auth.ts#L99

Should copy the existing env for the auth command execution.

            const env = { ...process.env };

[Stasmo]

Looks like the original fix was merged into master instead of main, and never made it to release.

[cjihrig]

Thanks for raising this. Would you be open to sending a PR (preferably with a regression test)?

[cjihrig]

Fixed in #2580