Add ability to hide/show notification free user cap over limit

What does this MR do and why?

introduces a feature flag that will allow us to enable free user cap notifications without showing alerts or the impact of them to the users.

This will allow us to measure performance better of the user count calculation before free user cap rollout - see #384527

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.

Related to #384527