Administration: Fix the red links on the Media Modal.

The custom link colors for admin scheme colors were overriding the danger color.

Props kebbet, dlh.
Fixes #50547.

Built from https://develop.svn.wordpress.org/trunk@48643


git-svn-id: https://core.svn.wordpress.org/trunk@48405 1a063a9b-81f0-0310-95a4-ce76da25c4cd