Prevent pre-enforcement and threshold banners both displaying

What does this MR do and why?

This implements https://gitlab.com/gitlab-org/gitlab/-/issues/432082

Screenshots or screen recordings

Before	After	After - over limit

How to set up and validate locally

Use these commands in rails console:

1. Gitlab::CurrentSettings.update!(automatic_purchased_storage_allocation: true)
2. Gitlab::CurrentSettings.update!(enforce_namespace_storage_limit: true)
3. Plan.free.actual_limits.update!(notification_limit: 5*1024)
4. Plan.free.actual_limits.update!(enforcement_limit: 10*1024)
5. Plan.free.actual_limits.update!(storage_size_limit: 5*1024)
6. Project.find(29).statistics.update(repository_size: 8.gigabytes)
   1. Sidekiq.redis(&:flushdb)
   2. Namespaces::ScheduleAggregationWorker.perform_sync(89)
   3. Namespaces::RootStatisticsWorker.perform_sync(89)
7. Feature.enable(:namespace_storage_limit_show_preenforcement_banner, Group.find(89))
8. Feature.enable(:namespace_storage_limit, Group.find(89))

Check the following scenarios:

1. Namespace with 8.gigabytes of used storage: only show pre-enforcement banner
2. Namespace with 12.gigabytes of used storage: only show enforcement banner
3. All the actual_limits set to 5*1024
4. Namespace with 8.gigabytes of used storage: show enforcement banner
5. Namespace with 4.gigabytes of used storage: shows threshold banner

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.