Rollup merge of #103851 - viandoxdev:103816_bootstrap_fix_json_doc, r=jyn514

Fix json flag in bootstrap doc

Fix the `--json` flag not working with x.py (Closes #103816)

While this works I'm not sure about the `should_run` of `JsonStd`, had to change it because https://github.com/rust-lang/rust/blob/ab5a2bc7316012ee9b2a4a4f3821673f2677f3d5/src/bootstrap/builder.rs#L334 would match with JsonStd and remove the paths that Std matched. So I did [this](https://github.com/viandoxdev/rust/blob/ffd4078264c4892b5098d6191e0adfe3564d62ca/src/bootstrap/doc.rs#L526-L534) but that looks more like a hack/workaround than anything. I'm guessing there's something to do with the default condition thing but idk how it works

diff --cc src/bootstrap/doc.rs
Simple merge

diff --cc src/bootstrap/test.rs
Simple merge