minor #61371 chore: PHP CS Fixer - restore PHP / PHPUnit rulesets (keradus)

This PR was squashed before being merged into the 7.4 branch.

Discussion
----------

 chore: PHP CS Fixer - restore PHP / PHPUnit rulesets

| Q             | A
| ------------- | ---
| Branch?       | 7.4
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Issues        | Fix CS <!-- prefix each issue number with "Fix #", no need to create an issue if none exists, explain below instead -->
| License       | MIT

relates to symfony/symfony@5d4e211#r163638626 , showing:
- possible improvements to codebase that those ruleset can still offer (especially when targetting newest possible target version)
- and also preventing old way to still be in use, if someone forget to use new syntax/methods

with love by [PHP Coding Standards Fixer](https://cs.symfony.com/)

Commits
-------

92940de5e52  chore: PHP CS Fixer - restore PHP / PHPUnit rulesets

Author: nicolas-grekas

Read/Splitter.php

@@ -79,7 +79,7 @@ private static function createListBoundaries(\Iterator $tokens): \Iterator
             }
 
             [$value, $position] = $token;
-            $offset = $offset ?? $position;
+            $offset ??= $position;
 
             if (isset(self::NESTING_CHARS[$value])) {
                 ++$level;

Read/StreamReaderGenerator.php

@@ -76,7 +76,7 @@ public function generate(Type $type, bool $decodeFromStream, array $options = []
         try {
             $this->fs->dumpFile($tmpFile, $php);
             $this->fs->rename($tmpFile, $path);
-            $this->fs->chmod($path, 0666 & ~umask());
+            $this->fs->chmod($path, 0o666 & ~umask());
         } catch (IOException $e) {
             throw new RuntimeException(\sprintf('Failed to write "%s" stream reader file.', $path), previous: $e);
         }

Write/StreamWriterGenerator.php

@@ -76,7 +76,7 @@ public function generate(Type $type, array $options = []): string
         try {
             $this->fs->dumpFile($tmpFile, $php);
             $this->fs->rename($tmpFile, $path);
-            $this->fs->chmod($path, 0666 & ~umask());
+            $this->fs->chmod($path, 0o666 & ~umask());
         } catch (IOException $e) {
             throw new RuntimeException(\sprintf('Failed to write "%s" stream writer file.', $path), previous: $e);
         }