Header: reevaluate webkit tap hightlight

[mfranzke]

          It is for mobile devices only:

When you click on a button for example there is a short overlay container (light blue) indicating that the item was clicked. But in the current mobile navigation, we open up another drawer layer. With the tap-highlight enabled the button below the new drawer layer will be highlighted which looks very wired. Moreover, the new drawer layer is an indicator as well. So we don't need this tap highlight in the navigation.

But it makes sense for other components like the regular button etc., and we should check if we want to use a custom color for this, like "informational". But this is fine-tuning.

Originally posted by @nmerget in https://github.com/db-ui/mono/pull/441#discussion_r1296918638