Add more default group tests and fix default groups for `uv add` (#13182)
## Summary
Brings in a bug fix for `uv add` w.r.t default groups from
https://github.com/astral-sh/uv/pull/12964, see comment:
https://github.com/astral-sh/uv/pull/12964#discussion_r2060775131
Adds additional test coverage for default groups in `run`, `remove`,
`add`.
## Test Plan
`cargo test`