Exit block region button hidden when navigation module is installed

Problem/Motivation

When the new navigation module is installed and you demonstrate the regions in the block layout the back button is hidden

Steps to reproduce

Install navigation
Go to /admin/structure/block
Click Demonstrate block regions (Olivero)
See that the back button is hidden behind the navigation bar

Proposed resolution

Not sure best fix but it shouldn't be hidden

TBD

Remaining tasks

Determine best fix

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet