Update top spacing for layout page and content wrapper

What does this MR do and why?

Move padding-top for --top-bar-height to .content-wrapper for correct offsetTop value in getContentWrapperHeight util using .content-wrapper to provide header-height value for GlDrawer

Changelog: fixed

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. View issue e.g. http://127.0.0.1:3000/flightjs/Flight/-/issues/32
2. Press "Report abuse" menu option on comment
3. GlDrawer should be aligned to the correct top-position
4. This fix should also address any other usage of getContentWrapperHeight('.content-wrapper')
5. Toggle new navigation on/off to test with old/new navigation

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #410711 (closed)