Network Admin: Remove a superfluous description field and merge two similar strings.

props Hanni, SergeyBiryukov.
fixes #26260.
Built from https://develop.svn.wordpress.org/trunk@26478


git-svn-id: http://core.svn.wordpress.org/trunk@26376 1a063a9b-81f0-0310-95a4-ce76da25c4cd