Adjusts pre enforcement banner to include dashboard limit

What does this MR do and why?

Updates the pre-enforcement notification banner to include the dashboard limit in the title.

This addresses part 1 of https://gitlab.com/gitlab-org/gitlab/-/issues/432505#ask

Screenshots or screen recordings

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

Before	After

How to set up and validate locally

1. Enable pre-enforcement notifications as in Phase 1 of https://gitlab.com/gitlab-org/gitlab/-/issues/413810#enabling-rollout
2. Visit http://gdk.test:3000/admin/namespace_limits
3. Set a dashboard limit value to a size (in MiB) lower than one of your local groups
4. Set a notification limit value to match
5. Visit the group and view the banner
6. Checkout this branch and refresh - the title should update with the new value

MR acceptance checklist

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