Various local trait item iteration cleanups Adding a trait impl for `Foo` unconditionally affected all queries that are interested in a completely independent trait `Bar`. Perf has no effect on this. We probably don't have a good perf test for this tho. r? `@compiler-errors` I am unsure about https://github.com/rust-lang/rust/pull/139018/commits/9d05efb66f7b599eeacb5d2456f844fe4768e865 as it doesn't improve anything wrt incremental, because we still do all the checks for valid `Drop` impls, which subsequently will still invoke many queries and basically keep the depgraph the same. I want to do https://github.com/rust-lang/rust/blob/9549077a47099dc826039c051b528d1013740e6f/compiler/rustc_middle/src/ty/trait_def.rs#L141 but would leave that to a follow-up PR, this one changes enough things as it is