Resolve "Scrolling horz on iOS for the secondary nav is broken"
## What does this MR do?
Moves absolutely positioned `div`s outside of the scrolling container because mobile safari causes those elements to jump around on scroll.
## Are there points in the code the reviewer needs to double check?
Check on a real iPhone (was only able to check in iOS simulator)
## Why was this MR needed?
Mobile Safari.
## What are the relevant issue numbers?
Closes#18438
## Screenshots (if relevant)
See merge request !4869
Hide nav arrows by default
## What does this MR do?
- Fixes the arrow icon flashing on page load
- Removes settings dropdown at higher breakpoint
- Removes unneeded CSS
Closes#18941
## Screenshots (if relevant)
Arrow flashing bug:
Settings dropdown breaking nav:
<img src="/uploads/4351035f4cf8cb9fd892b621e6339e50/Screen_Shot_2016-06-21_at_4.25.50_PM.png" width="800px">
@alfredo1 would you mind double checking this to make sure the arrow flashing is definitely not happening?
See merge request !4843
Jacob SchatzandRobert Speicher
Phil Hughes
Annabel Dunstone