Test case files are not removed when a test case is removed from a rule

See for example:
https://github.com/w3c/wcag-act-rules/pull/329

Inapplicable Example 1 from "Image has non-empty accessible name" is removed, but its [test case file ](https://github.com/w3c/wcag-act-rules/blob/main/content-assets/wcag-act-rules/testcases/23a2a8/cd3b3a4046451da9b9cc3e166c09d27583a2c30b.html) is not.