Simplify how admin color schemes are enqueued.

Removes a piece of [27111].

fixes #20729.

Built from https://develop.svn.wordpress.org/trunk@27203


git-svn-id: http://core.svn.wordpress.org/trunk@27060 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Remove accidental change in [27203]. see #20729.

Built from https://develop.svn.wordpress.org/trunk@27204


git-svn-id: http://core.svn.wordpress.org/trunk@27061 1a063a9b-81f0-0310-95a4-ce76da25c4cd