feature #22828 [Finder] Deprecate FilterIterator (ogizanagi)

This PR was merged into the 3.4 branch.

Discussion
----------

[Finder] Deprecate FilterIterator

| Q             | A
| ------------- | ---
| Branch?       | 3.3
| Bug fix?      | no
| New feature?  | no <!-- don't forget updating src/**/CHANGELOG.md files -->
| BC breaks?    | no
| Deprecations? | yes <!-- don't forget updating UPGRADE-*.md files -->
| Tests pass?   | yes
| Fixed tickets | https://github.com/symfony/symfony/pull/22820#pullrequestreview-39351934
| License       | MIT
| Doc PR        | N/A

Commits
-------

946066c [Finder] Deprecate FilterIterator

UPGRADE-3.4.md

@@ -1,6 +1,13 @@
 UPGRADE FROM 3.3 to 3.4
 =======================
 
+Finder
+------
+
+ * The `Symfony\Component\Finder\Iterator\FilterIterator` class has been
+   deprecated and will be removed in 4.0 as it used to fix a bug which existed 
+   before version 5.5.23/5.6.7
+
 Validator
 ---------
 

UPGRADE-4.0.md

@@ -145,6 +145,8 @@ Finder
 ------
 
  * The `ExceptionInterface` has been removed.
+ * The `Symfony\Component\Finder\Iterator\FilterIterator` class has been
+   removed as it used to fix a bug which existed before version 5.5.23/5.6.7
 
 Form
 ----

src/Symfony/Component/Finder/CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+3.4.0
+-----
+
+ * deprecated `Symfony\Component\Finder\Iterator\FilterIterator`
+
 3.3.0
 -----
 

src/Symfony/Component/Finder/Iterator/FilterIterator.php

@@ -18,6 +18,8 @@ namespace Symfony\Component\Finder\Iterator;
  * @see https://bugs.php.net/68557
  *
  * @author Alex Bogomazov
+ *
+ * @deprecated since 3.4, to be removed in 4.0.
  */
 abstract class FilterIterator extends \FilterIterator
 {

src/Symfony/Component/Finder/Tests/Iterator/FilterIteratorTest.php

@@ -13,6 +13,8 @@ namespace Symfony\Component\Finder\Tests\Iterator;
 
 /**
  * @author Alex Bogomazov
+ *
+ * @group legacy
  */
 class FilterIteratorTest extends RealIteratorTestCase
 {