Administration: Remove the smiley from overly happy "No activity yet!" message on Dashboard.

Props francoist, karmatosed, ibdz, estelaris, nrqsnchz, Presskopp.
Fixes #48387.
Built from https://develop.svn.wordpress.org/trunk@47592


git-svn-id: https://core.svn.wordpress.org/trunk@47367 1a063a9b-81f0-0310-95a4-ce76da25c4cd