Auto merge of #69198 - ollie27:rustbuild_rustdoc-js, r=Mark-Simulacrum
Auto merge of #69198 - ollie27:rustbuild_rustdoc-js, r=Mark-Simulacrum

Fix running rustdoc-js test suite individually

Without `Compiletest.path` set running `x.py test src/test/rustdoc-js` would run the `rustdoc-js` test suite with everything filtered out.

As this was the only place setting `Compiletest.path` to `None` this removes the `Option` wrapper as well.

aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust