Rollup merge of #152116 - GuillaumeGomez:fix-rustdoc-gui-flaky, r=GuillaumeGomez

Remove rustdoc GUI flaky test

Part of rust-lang/rust#93784.

Originally, this test was checking more things (original version is [here](https://github.com/rust-lang/rust/commit/6bbbff5189604d8a187e5837bd763e303d7a79d6)), now it only checks that the `searchIndex` variable is global. However, we already are forced to check it in the `rustddoc-js[-std]` testsuites so I think it's safe to say that it's superfluous and definitely not worth all the CI flakyness it created.

r? ghost

tests/rustdoc-gui/globals.goml

@@ -1,20 +0,0 @@
-// Make sure search stores its data in `window`
-// It needs to use a global to avoid racing on search-index.js and search.js
-// https://github.com/rust-lang/rust/pull/118961
-include: "utils.goml"
-
-// URL query
-go-to: "file://" + |DOC_PATH| + "/test_docs/index.html?search=sa"
-wait-for: "#search-tabs"
-wait-for-window-property-false: {"searchIndex": null}
-
-// Form input
-go-to: "file://" + |DOC_PATH| + "/test_docs/index.html"
-call-function: ("perform-search", {"query": "Foo"})
-wait-for-window-property-false: {"searchIndex": null}
-
-// source sidebar
-go-to: "file://" + |DOC_PATH| + "/src/test_docs/lib.rs.html"
-click: "#sidebar-button"
-wait-for: "#src-sidebar details"
-assert-window-property: {"searchIndex": null}