Rollup merge of #70228 - lzutao:patch-1, r=Mark-Simulacrum
Rollup merge of #70228 - lzutao:patch-1, r=Mark-Simulacrum

Remove CARGO_BUILD_TARGET from bootstrap.py

Closes #70208

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