[red-knot] add special case for float/complex (#16166)
When adjusting the existing tests, I aimed to avoid dealing with the
special case in other tests if it's not necessary to do so (that is,
avoid using `float` and `complex` as examples where we just need "some
type"), and keep the tests for the special case mostly collected in the
mdtest dedicated to that purpose.
Fixes https://github.com/astral-sh/ruff/issues/14932
