Re-initialize $wp_locale global after changing the default textdomain on installation screens.

props ocean90.
fixes #29452.
Built from https://develop.svn.wordpress.org/trunk@29669


git-svn-id: http://core.svn.wordpress.org/trunk@29443 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Use wp_admin_css() to enqueue stylesheets in setup-config.php.

fixes #29464.
Built from https://develop.svn.wordpress.org/trunk@29670


git-svn-id: http://core.svn.wordpress.org/trunk@29444 1a063a9b-81f0-0310-95a4-ce76da25c4cd