[TASK] Reduce memory usage of a greedy unit test

> Build/Scripts/runTests.sh

Before:
Memory: 469.06 MB

After:
Memory: 373.02 MB

Reason: phpunit executes data providers early and keeps
data sets in memory. The "xml parser big content" tests
create megabytes of data kept in memory. Moving the data
generation from data providers to the test execution
reduces overall memory usage significantly.

Resolves: #104076
Releases: main, 12.4, 11.5
Change-Id: I0ad49824fc1d4c309158b74474853d36af22ffb5
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84668


Reviewed-by: Andreas Kienast <a.fernandez@scripting-base.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Andreas Kienast <a.fernandez@scripting-base.de>

typo3/sysext/core/Tests/Unit/Serializer/Typo3XmlParserTest.php

@@ -347,52 +347,28 @@ final class Typo3XmlParserTest extends UnitTestCase
         );
     }
 
-    /**
-     * @return array[]
-     */
     public static function decodeHandlesBigXmlContentDataProvider(): array
     {
         return [
-            '1mb' => [
-                '<?xml version="1.0" encoding="utf-8" standalone="yes"?>
-                <T3FlexForms>
-                    <data>
-                        <field index="settings.persistenceIdentifier">
-                            <value index="vDEF">' . str_repeat('1', 1024 * 1024) . '</value>
-                        </field>
-                    </data>
-                </T3FlexForms>',
-                str_repeat('1', 1024 * 1024),
-            ],
-            '5mb' => [
-                '<?xml version="1.0" encoding="utf-8" standalone="yes"?>
-                <T3FlexForms>
-                    <data>
-                        <field index="settings.persistenceIdentifier">
-                            <value index="vDEF">' . str_repeat('1', 5 * 1024 * 1024) . '</value>
-                        </field>
-                    </data>
-                </T3FlexForms>',
-                str_repeat('1', 5 * 1024 * 1024),
-            ],
-            '10mb' => [
-                '<?xml version="1.0" encoding="utf-8" standalone="yes"?>
-                <T3FlexForms>
-                    <data>
-                        <field index="settings.persistenceIdentifier">
-                            <value index="vDEF">' . str_repeat('1', 10 * 1024 * 1024) . '</value>
-                        </field>
-                    </data>
-                </T3FlexForms>',
-                str_repeat('1', 10 * 1024 * 1024),
-            ],
+            '1mb' => [1],
+            '5mb' => [5],
+            '10mb' => [10],
         ];
     }
 
     #[DataProvider('decodeHandlesBigXmlContentDataProvider')]
     #[Test]
-    public function decodeHandlesBigXmlContent(string $input, string $testValue): void
+    public function decodeHandlesBigXmlContent(int $megabytes): void
     {
+        $input = '<?xml version="1.0" encoding="utf-8" standalone="yes"?>
+            <T3FlexForms>
+                <data>
+                    <field index="settings.persistenceIdentifier">
+                        <value index="vDEF">' . str_repeat('1', $megabytes * 1024 * 1024) . '</value>
+                    </field>
+                </data>
+            </T3FlexForms>';
+        $testValue = str_repeat('1', $megabytes * 1024 * 1024);
         $xmlDecoder = new Typo3XmlParser();
         $expected = [
             'data' => [