Remove free-spacing modifier and extra spaces from wp_extract_urls() pattern.

fixes #28222.
Built from https://develop.svn.wordpress.org/trunk@28933


git-svn-id: http://core.svn.wordpress.org/trunk@28731 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Move ms-load.php and ms-default-constants.php inclusion back to ms-settings.php to avoid breaking WP-CLI.

Use require_once() to allow for ms-settings.php to be included multiple times while testing.

props jeremyfelt.
see #27884.
Built from https://develop.svn.wordpress.org/trunk@28934


git-svn-id: http://core.svn.wordpress.org/trunk@28732 1a063a9b-81f0-0310-95a4-ce76da25c4cd