[Ban AI] Only show beta and experiment on the top-level settings

Description

Offering the ability to enable Beta and Experiment AI features at the top-level settings (admin settings on self-managed, or top-level group settings on .com).

Status

This work was blocked by [Ban AI] Creation of ai_experiment_features_ena... (#460725 - closed) (All Clear - Issue Closed)

Design

⚠ Final design and UI copy in Figma⚠

Top-level	Subgroup

Scope of this issue

I'm pretty sure this is actually already implemented like this. I think the scope of this issue is to double-check that this works as intended.

For example, here's screenshots of production .com:

Top-level group	Subgroup