Rollup merge of #137955 - Noratrieb:rustdoc-json-long-lines, r=aDotInTheVoid,jieyouxu

Always allow rustdoc-json tests to contain long lines

The rustdoc-json test syntax often requires very long lines, so the checks for long lines aren't really useful.

`@aDotInTheVoid` told me she'd like this and

r? jieyouxu

you're gonna tell me that the implementation is terrible. at least the performance seems reasonable: 2.5s after and 2.5s before.

Author: matthiaskrgr