Rollup merge of #139789 - lcnr:opaques-auto-trait-leakage, r=compiler-errors

do not unnecessarily leak auto traits in item bounds

fixes rust-lang/trait-system-refactor-initiative#158

Not a fix for rust-lang/trait-system-refactor-initiative#173 as you may have realized/tried yourself, cc #139788. However, fixing this feels desirable regardless and I don't see any reason not to.

r? ```@compiler-errors```

Author: Zalathar