Rollup merge of #145669 - notriddle:test-js-search-scripts-path, r=GuillaumeGomez

rustdoc-search: GUI tests check for `//` in URL

Follow up rust-lang/rust#145650

When this fails, you get output that looks like:

    /home/user/rust/tests/rustdoc-gui/search-result-impl-disambiguation.goml search-result-impl-disambiguation... FAILED
    [ERROR] `tests/rustdoc-gui/utils.goml` around line 49
        from `tests/rustdoc-gui/search-result-impl-disambiguation.goml` line 25: JS errors occurred: Event: Event

Making the error message more informative requires patching browser-ui-test.

Author: jhpratt