Auto merge of #33074 - mitaa:rdoc-irlst, r=alexcrichton

rustdoc: Fix the strip-hidden `ImplStripper`

Instead of stripping impls which reference *stripped* items, we keep impls which reference *retained* items. We do this because when we strip an item we immediately return, and do not recurse into it - leaving the contained items non-stripped from the point of view of the `ImplStripper`.

fixes #33069

r? @alexcrichton

diff --cc src/librustdoc/passes.rs
Simple merge