[Origin] Replace Shields orange lion with Brave Origin icon in standalone version #56950

Description

As discussed in https://bravesoftware.slack.com/archives/C06RMD0C7U2/p1782839357269209

We're replacing the Shields icon in Origin Standalone with the Origin icon.

Spec:

• Shields UP icon -> brave-icon-only-face in Nala
• Shields DOWN icon -> brave-icon-only-face-disabled in Nala
• Color: icon/Default (Or, same color as the rest of the icons in the urlbar)

Design files:
https://www.figma.com/design/IwYu4Yjt3wYFG59zcwWSGu/%F0%9F%A6%81-Brave-Origin?node-id=2722-34229&t=PUGIuJqUcqW72GcR-1

Shields UP

Shields DOWN