Auto merge of #127117 - Urgau:non_local_def-syntactic, r=BoxyUwU

Rework `non_local_definitions` lint to only use a syntactic heuristic

This PR reworks the `non_local_definitions` lint to only use a syntactic heuristic, i.e. not use a type-system logic for whenever an `impl` is local or not.

Instead the new logic wanted by T-lang in https://github.com/rust-lang/rust/issues/126768#issuecomment-2192634762, which is to consider every paths in `Self` and `Trait` and to no longer use the type-system inference trick.

`@rustbot` labels +L-non_local_definitions
Fixes #126768