Dashboard edit button shown on mobile

[flash1293]

Kibana version: master

Describe the bug: Editing dashboards on mobile devices is not supported. Because of this the Edit menu button should be hidden if the viewport is too small (see #29896 ) It seems like this broke at some place. (Maybe during kbn-top-nav migration - ping @lizozom )

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[cchaos]

This is a regression since 7.4. In Dashboards, we hide the "Edit" top nav item from mobile devices by passing down utility classes. This seems to have broken during the React-ification of the Top Nav component (#40262).

This is how we were passing down the class:

kibana/src/legacy/core_plugins/kibana/public/dashboard/top_nav/get_top_nav_config.ts

Lines 89 to 91 in 479177a

	// We want to hide the "edit" button on small screens, since those have a responsive
	// layout, which is not tied to the grid anymore, so we cannot edit the grid on that screens.
	className: 'eui-hideFor--s eui-hideFor--xs',

And this is where is needs to be applied to the nav item.

kibana/src/legacy/core_plugins/navigation/public/top_nav_menu/top_nav_menu_item.tsx

Lines 42 to 51 in 479177a

	const btn = (
	<EuiButtonEmpty
	size="xs"
	isDisabled={isDisabled()}
	onClick={handleClick}
	data-test-subj={props.testId}
	>
	{capitalize(props.label || props.id!)}
	</EuiButtonEmpty>
	);