Coding Standards: Break out of the inner loop in make_site_theme_from_default().

This more closely matches the previous behavior with multiple `if`/`elseif` statements.

Follow-up to [55688].

See #56982.

git-svn-id: https://develop.svn.wordpress.org/trunk@55698 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/upgrade.php

@@ -3339,6 +3339,7 @@ function make_site_theme_from_default( $theme_name, $template ) {
 			foreach ( $headers as $header => $value ) {
 				if ( strpos( $line, $header ) !== false ) {
 					$line = $header . ' ' . $value;
+					break;
 				}
 			}