Auto merge of rust-lang#102340 - JakobDegen:pass-manager-simplificati…

…on, r=oli-obk

Split phase change from `MirPass`

The main goal here is to simplify the pass manager logic. `MirPass` no longer contains the `phase_change` method, and `run_passes` instead accepts an `Option<PhaseChange>`. The hope is that this addresses the comments (and maybe perf regression) from rust-lang#99102 .

r? `@oli-obk` cc `@RalfJung`