[Ban AI] Decommission Experimental Settings feature from Group & Admin Permission Settings

Context

🚨 THIS WORK IS CURRENTLY BLOCKED BY THE FOLLOWING Issue(s): #480026 (closed) [Ban AI] Remove Feature Flags for Group, Admin and Project Duo Settings

We need to decommission the _experimental_settings.html.haml component in Group Settings > Edit via Permissions since there is a new Vue component and section to handle the updated functionality via this MR.

Scope of this issue

• Remove _experimental_settings.html.haml component (and associated specs)