Display all seats user banner when there is an overage

What does this MR do and why?

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/470602+. This MR changes the conditions to display the banner, given the "read-only" banner has been/is being removed (see here: !158571 (merged))

MR acceptance checklist

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Screenshots or screen recordings

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Used seats == seats in sub	Used seats >= seats in sub

How to set up and validate locally

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