Coding Standards: Remove a one-time $sql variable in network_domain_check().

This allows the `$wpdb::prepare()` call to be picked up correctly by PHPCS.

Follow-up to [28712].

Props aristath, poena, afercia, SergeyBiryukov.
See #63168.

git-svn-id: https://develop.svn.wordpress.org/trunk@60096 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-admin/includes/network.php

@@ -19,10 +19,10 @@
 function network_domain_check() {
 	global $wpdb;
 
-	$sql = $wpdb->prepare( 'SHOW TABLES LIKE %s', $wpdb->esc_like( $wpdb->site ) );
-	if ( $wpdb->get_var( $sql ) ) {
+	if ( $wpdb->get_var( $wpdb->prepare( 'SHOW TABLES LIKE %s', $wpdb->esc_like( $wpdb->site ) ) ) ) {
 		return $wpdb->get_var( "SELECT domain FROM $wpdb->site ORDER BY id ASC LIMIT 1" );
 	}
+
 	return false;
 }