Rollup merge of #43374 - stjepang:fix-sort-randomization-comment, r=alexcrichton
Rollup merge of #43374 - stjepang:fix-sort-randomization-comment, r=alexcrichton

Clarify that sort_unstable is deterministic

@frankmcsherry complained that the documentation said "it is randomized but deterministic", which is a contradictory statement.

This PR uses a different and clearer wording.

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