Move required pipeline configuration to Ultimate

Overview

The required pipeline configuration feature is deprecated in GitLab 14.8 for Premium customers and is scheduled for removal in GitLab 15.0. This feature is not deprecated for GitLab Ultimate customers.

Proposal

• The required pipeline configuration feature will be moved to the Ultimate tier by default
• GitLab will preserve a way via feature flag or another similar capability of enabling this for individual Premium customers as needed (see requirement from @ogolowinski)

Rationale

This change to move the feature to GitLab's Ultimate tier is intended to help our features better align with our pricing philosophy as we see demand for this feature originating primarily from Executives. This change will also help GitLab remain consistent in its tiering strategy with the other related Ultimate-tier features of security policies and compliance framework pipelines.