Themes: Remove extra whitespace from `wp-admin/includes/ajax-actions.php` and...

Themes: Remove extra whitespace from `wp-admin/includes/ajax-actions.php` and `wp-admin/includes/theme.php`.

Follow-up to [47816].

See #48491.
Built from https://develop.svn.wordpress.org/trunk@47818


git-svn-id: https://core.svn.wordpress.org/trunk@47594 1a063a9b-81f0-0310-95a4-ce76da25c4cd