Update What's New - Sidebar navigation remains until all features read
For the `What's new` sidebar navigation button, currently it appears when there's new release, and disappears when the user clicks it. We want to update that to: > Ideally when a user reads an article and then backs out of the article, both the unread indicator is cleared, and the count that appears in the badge decreases. Then once that count gets to 0, the What's new section gets shifted to the Help menu as soon as the What's new drawer is closed. https://gitlab.com/gitlab-org/gitlab/-/merge_requests/201798#note_2703438678
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