bats test: add a backup image to avoid network errors

[adamqqqplay]

Relevant Issue (if applicable)

In some cases, the image source provided by ghcr.io is not very stable and may cause the test to fail.

Details

This patch adds a backup image to avoid network errors. When the test fails, the backup image is retried.

Test passed in: https://tone.openanolis.cn/ws/nrh4nnio/test_result/117548?tab=1

Types of changes

What types of changes does your PullRequest introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation Update (if none of the other choices apply)

Checklist

Go over all the following points, and put an x in all the boxes that apply.

• I have updated the documentation accordingly.
• I have added tests to cover my changes.

[yqleng1987]

Test passed！

[imeoer]

LGTM!

[adamqqqplay]

Codecov CI are broken and can be ignored for now.