[CI]: fix TestImageHistory to not hardcode duration

[apostasie]

Description

TestImageHistory currently fails every year, as it hard codes a string mentioning "created X years ago".

This was just temporarily addressed in #4058 but will fail again next year.

Steps to reproduce the issue

No response

Describe the results you received and expected

This test should be modified to remove the hard coded string so that it does not fail every year...

What version of nerdctl are you using?

main

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

None

Host information

No response

[apostasie]

@AkihiroSuda +good-first-issue

[biubiubiuboomboomboom]

i'm interested in taking on this issue.

[apostasie]

@biubiubiuboomboomboom sure, go for it! Thanks.

[apostasie]

Fixed by #4083