Adds support for unsetting of env vars

[Harkishen-Singh]

Signed-off-by: Harkishen-Singh harkishensingh@hotmail.com

Fixes: #8476

Behaviour before this PR

[hsingh@localhost out]$ ./minikube docker-env --unset
🤷  The control plane node must be running for this command
👉  To fix this, run: "minikube start"

Behaviour after this PR

[hsingh@localhost out]$ ./minikube docker-env --unset
unset DOCKER_TLS_VERIFY DOCKER_HOST DOCKER_CERT_PATH MINIKUBE_ACTIVE_DOCKERD

Reference: #8476 (comment)

Explanation:
The unsettling of env-vars in docker should be independent of whether the docker-machine is running or not. This is minikube specific issue and was occurring due co := mustload.Running(cname). Moving the unset statements up, before the running-checks solves the issue. Similar is the situation for podman.

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[k8s-ci-robot]

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Harkishen-Singh
To complete the pull request process, please assign medyagh
You can assign the PR to them by writing /assign @medyagh in a comment when ready.

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[minikube-bot]

Can one of the admins verify this patch?

[Harkishen-Singh]

In reference to #8476 (comment)

[Harkishen-Singh]

/assign @medyagh

[medyagh]

@Harkishen-Singh thank you for this PR, do you mind putting in the PR description the Before and After this PR's output and explain how it is fixing the issue?

[Harkishen-Singh]

@medyagh sure.

[Harkishen-Singh]

@medyagh Done!

[medyagh]

@Harkishen-Singh Thank you very much for this helpful PR ! I hope I get to see more contributions from you

[Harkishen-Singh]

@medyagh definitely! Thank you.

[medyagh]

@Harkishen-Singh please feel free to take issues labeled help-wanted or good-first-issue
https://github.com/kubernetes/minikube/issues?q=is%3Aopen+is%3Aissue+label%3A%22help+wanted%22

[Harkishen-Singh]

@medyagh sure.