Rollup merge of #154709 - Jamesbarford:chore/revert-ty-type-alias, r=lcnr

Revert `Ty` type alias in `rustc_type_ir`

Reverting (rust-lang/rust#154270) the creation and use of `Ty` type alias in `rustc_type_ir` that was causing problems with Rust Analyser, see [discussion on Zulip](https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/.23154270.20.28Ty.20alias.29.20triggers.20many.20bogus.20RA.20errors/with/583209227) for more

r? @lcnr

Author: JonathanBrouwer