restrict astrocut tests

[braingram]

Description

astrocut tests seem to be downloading files which is randomly failing. See: https://github.com/asdf-format/asdf/actions/runs/7718257705/job/21039125750?pr=1745#step:10:463 and: https://github.com/asdf-format/asdf/actions/runs/7717678770/job/21037293335#step:10:559

As we're mainly interested in making sure the asdf portion of astrocut is not impacted by changes here this PR restricts the tests to those defined in test_asdf_cut.

The change here is similar to restrictions placed on other downstream tests:

• weldx
• sunpy

Checklist:

• [ ] pre-commit checks ran successfully
• [ ] tests ran successfully
• [ ] for a public change, a changelog entry was added
• [ ] for a public change, documentation was updated
• [ ] for any new features, unit tests were added