`std::raw::Vec` comes before `std::vec::Vec` in searching rustdoc

[edwardw]

When searching for "vec" in rustdoc, std::raw::Vec comes before std::vec::Vec, which is rather unfortunate. It would be more appropriate the other way around.

[thestinger]

This is covered by #12938 and #11875 because the old representation is going to be completely removed, along with that support code.