[6.x] Remove background blur from many places

[JayGeorge]

Description of the Problem

As per #13620, the background blur removes the possibility of referencing the underlying content.

What this PR Does

• Closes [6.x] Reconsider backdrop blur usage #13620
• Removes the background blur components where you might need to reference the background.
• The blurred background remains on modals, and the command palette
• Removes backdrop-blur-[10px] from the architectural lines. This is no longer needed now that we're using a solid color on that panel
• Remove a utility class that wasn't used

How to Reproduce

1. Edit a blueprint and view the blur effect on stacks in the background