Drop allow-by-default lint

Co-authored-by: Urgau <3616612+Urgau@users.noreply.github.com>

Author: Mark-Simulacrum

RELEASES.md

@@ -10,7 +10,6 @@ Language
 - [Make async-fn-in-trait implementable with concrete signatures](https://github.com/rust-lang/rust/pull/120103/)
 - [Make matching on NaN a hard error, and remove the rest of illegal_floating_point_literal_pattern](https://github.com/rust-lang/rust/pull/116284/)
 - [static mut: allow mutable reference to arbitrary types, not just slices and arrays](https://github.com/rust-lang/rust/pull/117614/)
-- [Add `non_local_definitions` lint for non-local `impl` definitions in functions](https://github.com/rust-lang/rust/pull/120393/)
 - [Add `non_contiguous_range_endpoints` lint for singleton gaps after exclusive ranges](https://github.com/rust-lang/rust/pull/118879/)
 - [Add `wasm_c_abi` lint for use of older wasm-bindgen versions](https://github.com/rust-lang/rust/pull/117918/)
   This lint only works with Cargo.