Auto merge of #34587 - ollie27:rustdoc_prim_titles, r=steveklabnik

rustdoc: Remove paths from primitive page <title> tags

Currently primitive pages have a title like "std::u8 - Rust" this changes
it to "u8 - Rust" as "std::u8" is the name of a module not a primitive
type.

diff --cc src/librustdoc/clean/mod.rs
Simple merge

diff --cc src/librustdoc/html/render.rs
Simple merge