Rollup merge of #124197 - GuillaumeGomez:move-duplicated-code, r=notr…

…iddle

Move duplicated code in functions in `tests/rustdoc-gui/notable-trait.goml`

It also allowed me to add some new common test like:

```
        assert-position: (
            "//*[`@class='tooltip` popover']",
            {"x": |popover_x|}
        )
```

r? `@notriddle`