Rollup merge of #139307 - xizheyin:issue-139296, r=joboet

std: Add performance warnings to HashMap::get_disjoint_mut

Closes #139296

The `get_disjoint_mut` in `HashMap` also performs a complexity O(n^2) check. So we need to be reminded of that as well.

https://github.com/rust-lang/hashbrown/blob/b5b0655a37e156f9798ac8dd7e970d4adba9bf90/src/raw/mod.rs#L1216-L1220

Author: matthiaskrgr