Auto merge of #132666 - dingxiangfei2009:skip-if-let-rescope-lint, r=…

…compiler-errors

Skip `if-let-rescope` lint unless requested by migration

Tracked by #124085
Related to rust-lang/rust#131984 (comment)

Given that `if-let-rescope` is a lint to be enabled globally by an edition migration, there is no point in extracting the precise lint level on the HIR expression. This mitigates the performance regression discovered by the earlier perf-run.

cc `@Kobzol` `@rylev` `@traviscross` I propose a `rust-timer` run to measure how much performance that we can recover from the mitigation. 🙇