Fixed bug where tmp dir incorrectly set for Snap package manager

[spowelljr]

Fixes: #10407

Background info:
The original issue was that starting minikube installed via Snap (package manager) would result in the error:

prepare kic ssh: copying pub key: docker copy /tmp/tmpf-memory-asset150446131 into minikube:/home/docker/.ssh/authorized_keys, output: lstat /tmp/tmpf-memory-asset150446131: no such file or directory

This is due to Snap only allowing packages to see their own view of the /tmp folder. In this case minikube copies a memory asset to the /tmp folder for Docker to later copy. Snap prevents Docker from seeing minikubes file and the above error occurs.

This PR:
This issue was attempted to be fixed in #10042, the correct way to solve this issue is to check if the binary is installed via Snap, and if it is, writes the memory asset to the users home directory instead. However, there was a bug included in the PR where instead of setting the tmp directory to the users home directory, it would try to find an env variable by the name of the users home directory and set that as the tmp directory. This env was not found and would return an empty string, passing an empty string to the function would fallback to using the default tmp directory and would fail. This fix simply removes the env check and sets the tmp directory to the users home directory.

[minikube-bot]

Can one of the admins verify this patch?

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: medyagh, spowelljr

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