Remove duplicate Runner security entry on navigation

What does this MR do and why?

The docs global navigation properly supports only having a single entry on the nav per page. Though the navigation can render more than one entry for a page, it only highlights and unfurls the first one. This leads to a situation where a users is taken away from the context they selected the entry in, and moved to another.

Here's a link the the page: http://eread-remove-duplicate-runner-security-nav-entry.35.193.151.162.nip.io/runner/security/ that highlights the entry that's left.

Screenshots, screen recordings, or links to review app

This is the context of the entry that's been removed:

This is the context of the entry that's been retained:

Merge request acceptance checklist

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