rust-lang/rust: core::num imports in libstd are unresolved

[lf-]

When I open library/std/src/num.rs, even with a cherry picked rust-lang/rust#86243, the imports of core::num::Wrapping and others are unresolved.

RA version: #9047 merged onto 660a896

Logs: unsure how to get good logs of project model, the ones I have don't say enough with project_model=debug in RA_LOG.

Config:

{
    "rust-analyzer.checkOnSave.overrideCommand": [
        "./x.py",
        "check",
        "--json-output"
    ],
    "rust-analyzer.rustfmt.overrideCommand": [
      "./build/x86_64-unknown-linux-gnu/stage0/bin/rustfmt"
    ],
    "rust-analyzer.cargo.runBuildScripts": false,
    "rust-analyzer.procMacro.enable": false
}

[lf-]

cc #8915

[flodiebold]

Probably same as #9203.