Remove unnecessary "not used" notation for filter parameters in wp-admin/includes/media.php.

Also add `@param` and `@return` descriptions.

See #28408.

Built from https://develop.svn.wordpress.org/trunk@28632


git-svn-id: http://core.svn.wordpress.org/trunk@28451 1a063a9b-81f0-0310-95a4-ce76da25c4cd