Welcome Tour NEXT: Add E2E test to ensure sanity

[chriskmnds]

Details

As of #56867 the Welcome Tour will use reference elements on the page to move the step closer to it (or fallback to the default position - bottom left).

Let's add an E2E test to ensure the reference elements are present on the page. Maybe not much more involving than that, but might explore whether the tour renders near also.

Checklist

• Changing one of the reference elements to an unknown selector should error.
• (Optional?) Tour renders near the reference element when defined.

Related

No response

[worldomonation]

FYI, something like this should not be an end to end test, but rather an integration level test. Unfortunately we do not have proper infrastructure in place yet for writing integration tests easily, but it is something the Quality Squad wants to do in the medium-term.