Auto merge of #131259 - ismailarilik:handle-potential-query-instabili…

…ty-lint-for-librustdoc, r=notriddle

Handle `librustdoc` cases of `rustc::potential_query_instability` lint

This PR removes `#![allow(rustc::potential_query_instability)]` line from [`src/librustdoc/lib.rs`](https://github.com/rust-lang/rust/blob/master/src/librustdoc/lib.rs#L23) and converts `FxHash{Map,Set}` types into `FxIndex{Map,Set}` to suppress lint errors.

A somewhat tracking issue: rust-lang/rust#84447

r? `@compiler-errors`