#73905 regressed several tests around associated type defaults

[ishitatsuyuki]

It seems that several test regression got ignored in #73905:

• cyclic defaults getting accepted in concrete impl
• default types no longer needs to be wf

While some of the other changes are acceptable, I think the changes listed above doesn't really get justified and seems to be a regression.

cc @matthewjasper

[matthewjasper]

• default types no longer needs to be wf

They do, this was moved to a different test file because the error prevents further compilation