Rollup merge of #64688 - rust-lang:clarify-tidy-since, r=alexreg
Rollup merge of #64688 - rust-lang:clarify-tidy-since, r=alexreg

Clarify the "since" tidy check

r? @pietroalbini

cc @alexreg

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