Tests manipulating credentials are not properly isolated from one another

[apostasie]

Description

All test manipulating credentials are loading and saving into the default docker config location.

This increases significantly the risk of cross-test pollution, false positives / negatives, and definitely prevents parallelization of tests.

Each test that relies on reading or saving credentials must use a dedicated temp location instead.

Steps to reproduce the issue

n.a.

Describe the results you received and expected

n.a.

What version of nerdctl are you using?

1.7.6

Are you using a variant of nerdctl? (e.g., Rancher Desktop)

None

Host information

No response