Custom roles requires Ultimate License

What does this MR do and why?

• Run license checks wherever we are using custom roles so that even with the feature flag on, only Ultimate customers can use this feature.
• #385466 (closed)

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

• Enable customizable_roles feature flag for a group
• Attempt to create a custom role for the group via instructions here: !104322 (merged)
• License error should be raised (custom role cannot be created)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.