Description

Tests using Setenv cannot be parallelized safely.

Instead, we should modify Env for whichever Cmd needs it without touching the global environment.

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