Rollup merge of #147489 - chenyukang:yukang-prefer-repeat-n, r=Kivooeo,oli-obk

Prefer to use repeat_n over repeat().take()

More from rust-lang/rust#147464, but batch processed with `ast-grep` to find and replace.

second commit add notes for library: rust-lang/rust@affaf53

r? ``@RalfJung``

Author: Zalathar