search: fix tour blocking monaco autocomplete
Created by: limitedmage
Monaco search autocomplete now shows over the onboarding tour.
This required upgrading Shepherd.js to 8.1+, which adds the stepsContainer
parameter which allows attaching the tour to someplace other than the end of the body. Attaching the tour to somewhere in the DOM tree above the search box will render the tour before the search box and allow the search box suggestions to show over the tour without any z-index fandangling.
Fixes #25618 (closed)