Clean up PHPStan ignoreErrors (#7982)

Author: samsonasik

phpstan.neon

@@ -280,12 +280,6 @@ parameters:
         # see https://github.com/rectorphp/rector-src/actions/runs/11798721617/job/32865546672?pr=6422#step:5:110
         - '#Doing instanceof PHPStan\\Type\\.+ is error\-prone and deprecated#'
 
-        # BC layer on Rector deprecation
-        -
-            paths:
-                - src/Configuration/RectorConfigBuilder.php
-            identifier: classConstant.deprecatedInterface
-
         # allowed internally only
         -
             message: '#Fetching (deprecated )?class constant (.*?) of (deprecated )?class (Rector\\Set\\ValueObject\\DowngradeLevelSetList|Rector\\Symfony\\Set\\(.*?))#'
@@ -416,13 +410,6 @@ parameters:
         - '#Class "Rector\\CodingStyle\\Rector\\String_\\SymplifyQuoteEscapeRector" is missing @see annotation with test case class reference#'
         - '#Class "Rector\\Php81\\Rector\\ClassMethod\\NewInInitializerRector" is missing @see annotation with test case class reference#'
 
-        # BC layer for FileWithoutNamespace node
-        -
-            path: src/PhpParser/Node/CustomNode/FileWithoutNamespace.php
-            identifier: symplify.forbiddenExtendOfNonAbstractClass
-
-        - message: '#Use @see \\Rector\\PhpParser\\Node\\FileNode instead#'
-
         # false positive
         -
             identifier: phpstanApi.varTagAssumption