Remove unnecessary printf(). fixes #25321.

Built from https://develop.svn.wordpress.org/trunk@25439


git-svn-id: http://core.svn.wordpress.org/trunk@25361 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Move to JSON for three api.wordpress.org endpoints. see #25311.

Built from https://develop.svn.wordpress.org/trunk@25441


git-svn-id: http://core.svn.wordpress.org/trunk@25362 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Move to JSON for the plugin and theme update-check API endpoints. see #25311.

Built from https://develop.svn.wordpress.org/trunk@25442


git-svn-id: http://core.svn.wordpress.org/trunk@25363 1a063a9b-81f0-0310-95a4-ce76da25c4cd