minor #61372 chore: PHP CS Fixer - update heredoc handling (keradus)

This PR was merged into the 7.4 branch.

Discussion
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 chore: PHP CS Fixer - update heredoc handling

| 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

Inspired while #61371 , but can be merged separately.

``@PHPxMigration`` and ``@Symfony`` ruleset have different config for those rules. I assume the difference is coming from supporting pre-7.2 PHP version earlier in the codebase, where heredoc closure and trailing comma had to be on separated lines - but it's no longer the case.

Can we benefit from newer PHP syntax and incorporate those changes? (yes, `trailing_comma_in_multiline`, part of ``@Symfony``, is already having this enabled!)
if so, i will also merge them into ``@Symfony`` ruleset itself afterwards.

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

Commits
-------

f9956227bb6  chore: PHP CS Fixer - update heredoc handling

Author: nicolas-grekas

Tests/Functional/ConfigDumpReferenceCommandTest.php

@@ -95,8 +95,9 @@ public function testDumpAtPath(bool $debug)
                 child2:               ~
 
 
-            EOL
-            , $tester->getDisplay(true));
+            EOL,
+            $tester->getDisplay(true)
+        );
     }
 
     #[TestWith([true])]

Tests/Functional/ContainerDebugCommandTest.php

@@ -183,8 +183,9 @@ public function testDescribeEnvVars()
 
              * UNKNOWN
 
-            TXT
-            , $tester->getDisplay(true));
+            TXT,
+            $tester->getDisplay(true)
+        );
 
         putenv('REAL');
     }

Tests/Functional/FragmentTest.php

@@ -33,8 +33,9 @@ public function testFragment($insulate)
             es
             --
             fr
-            TXT
-            , $client->getResponse()->getContent());
+            TXT,
+            $client->getResponse()->getContent()
+        );
     }
 
     public static function getConfigs()