rustdoc: don't ignore path distance for doc aliases

[lolbinarycat]

Ran into a bit of an issue due to the overloading of space (it needs to be a metachar for most searches, but not for doc aliases that have space in them). Not sure if I need to also need to account for other whitespace chars.

fixes #146214

r? @GuillaumeGomez

[rustbot]

Some changes occurred in HTML/CSS/JS.

cc @GuillaumeGomez, @jsha, @lolbinarycat

[rustbot]

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[yotamofek]

I think you meant "a space is both an alias...", but not sure

[rust-log-analyzer]

The job aarch64-gnu-llvm-20-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

Doc path: /checkout/obj/build/aarch64-unknown-linux-gnu/doc/alloc/index.html
[TIMING:end] doc::Std { build_compiler: Compiler { stage: 2, host: aarch64-unknown-linux-gnu, forced_compiler: false }, target: aarch64-unknown-linux-gnu, format: Html, crates: [] } -- 58.694
##[group]Testing stage2 rustdoc-js-std (aarch64-unknown-linux-gnu)
Testing alias-1.js ... OK
Testing alias-2.js ... TypeError: Cannot read properties of undefined (reading 'pathWithoutLast')
    at handleAlias (/checkout/obj/build/aarch64-unknown-linux-gnu/doc/static.files/search-ca977a4a.js:1:59572)
Bootstrap failed while executing `--stage 2 test --skip compiler --skip src`
Command `/usr/bin/node /checkout/src/tools/rustdoc-js/tester.js --crate-name std --resource-suffix 1.92.0 --doc-folder /checkout/obj/build/aarch64-unknown-linux-gnu/doc --test-folder /checkout/tests/rustdoc-js-std` failed with exit code 1
Created at: src/bootstrap/src/core/build_steps/test.rs:1008:27
Executed at: src/bootstrap/src/core/build_steps/test.rs:1035:17

Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:46:17
  local time: Tue Oct 14 21:16:32 UTC 2025
  network time: Tue, 14 Oct 2025 21:16:32 GMT
##[error]Process completed with exit code 1.
##[group]Run echo "disk usage:"