Auto merge of rust-lang#66066 - ecstatic-morse:remove-promotion-from-qualify-consts, r=eddyb

Remove promotion candidate gathering and checking from `qualify_consts.rs`

This makes promotion candidate gathering and checking the exclusive domain of `promote_consts`, but the `QualifyAndPromoteConsts` pass is still responsible for both const-checking and creating promoted MIR fragments.

This should not be merged until the beta branches on Nov. 5.

r? @eddyb

Author: bors