Media: Remove unused string.

props pavelevap.
fixes #29741.
Built from https://develop.svn.wordpress.org/trunk@30341


git-svn-id: http://core.svn.wordpress.org/trunk@30340 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Media: Remove another unused string.

props pavelevap.
see #29741.
Built from https://develop.svn.wordpress.org/trunk@30342


git-svn-id: http://core.svn.wordpress.org/trunk@30341 1a063a9b-81f0-0310-95a4-ce76da25c4cd