Auto merge of #146919 - lcnr:yeet-fast-path, r=fee1-dead

remove incorrect fast path

Using `tcx.is_copy_modulo_regions` drops information from the current `typing_env`. Writing a regression test for this is really hard. We need to prove `Copy` of something that doesn't directly reference a coroutine or an opaque, but does so indirectly.

cc rust-lang/rust#146813.

Author: bors