Fix tuist test clean

[fortmarek]

Short description 📝

tuist test --clean was not working properly since in the last release I completely removed a BuildAction - which, when running xcodebuild clean test ... resulted in a failure because there were no targets set up for building.

With the changes, the build action is not removed completely but contains only test targets which test results have not been cached. Added also appropriate acceptance test to catch this in the future.

Checklist ✅

• The code architecture and patterns are consistent with the rest of the codebase.
• The changes have been tested following the documented guidelines.
• The CHANGELOG.md has been updated to reflect the changes. In case of a breaking change, it's been flagged as such.
• In case the PR introduces changes that affect users, the documentation has been updated.