Auto merge of rust-lang#93963 - GuillaumeGomez:reduce-clean-type-size, r=notriddle

rustdoc: Reduce clean::Type size

There is no need to keep the `DefId` around since it's allow used to compute if we should show a cast or not. As such, we can simply directly store the boolean.

I think it's not what you had in mind `@camelid` but I guess it's still an improvement? 😉

It was discussed in rust-lang#93941.

r? `@camelid`

Author: bors