Administration: Apply admin notice functions in multisite.

Use `wp_get_admin_notice` and `wp_admin_notice` to handle multisite settings notices.

Props costdev.
See #57791.
Built from https://develop.svn.wordpress.org/trunk@56409


git-svn-id: http://core.svn.wordpress.org/trunk@55921 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/network/sites.php

@@ -358,7 +358,14 @@ if ( isset( $_GET['updated'] ) ) {
 	}
 
 	if ( ! empty( $msg ) ) {
-		$msg = '<div id="message" class="notice notice-success is-dismissible"><p>' . $msg . '</p></div>';
+		$msg = wp_get_admin_notice(
+			$msg,
+			array(
+				'type'        => 'success',
+				'dismissible' => true,
+				'id'          => 'message',
+			)
+		);
 	}
 }