Rollup merge of #68736 - TimDiekmann:remove-alloc, r=Amanieu
Rollup merge of #68736 - TimDiekmann:remove-alloc, r=Amanieu

Remove `Alloc` in favor of `AllocRef`

`AllocRef` was reexported as `Alloc` in #68529  in order to not break toolstate in the week before the next stable release.

r? @Amanieu

aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust