Rollup merge of rust-lang#126436 - GuillaumeGomez:reduce-gui-tests-fl…

…akyness, r=lqd

Reduce rustdoc GUI tests flakyness

Fixes rust-lang#126430.

r? `@notriddle`

tests/rustdoc-gui/utils.goml

@@ -13,6 +13,6 @@ define-function: (
         // Close the popover.
         click: "#settings-menu"
         // Ensure that the local storage was correctly updated.
-        assert-local-storage: {"rustdoc-theme": |theme|}
+        wait-for-local-storage: {"rustdoc-theme": |theme|}
     },
 )