Rollup merge of #125871 - fmease:fix-orphanck-opaques, r=lcnr

Orphanck[old solver]: Consider opaque types to never cover type parameters

This fixes an oversight of mine in #117164. The change itself has already been FCP'ed.

This only affects the old solver, the next solver already correctly rejects the added test since #117164.

r? ``@lcnr``

Author: matthiaskrgr