Deprecate Symfony level sets (#572)

* deprecate Symfony level set list, for huge performance hit, conflicting rule order in various version

* fixup! deprecate Symfony level set list, for huge performance hit, conflicting rule order in various version

config/sets/symfony/level/deprecated-level-set.php

@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+use Rector\Config\RectorConfig;
+
+return static function (RectorConfig $rectorConfig): void {
+    // this set was deprecated, due to overuse, conflicts and performance problems
+    // instead use one Symfony set at a time, and keep only up to latest Symfony version
+    // @see https://getrector.com/blog/5-common-mistakes-in-rector-config-and-how-to-avoid-them
+};