TASK: Remove obsolete special handling for DateTimeInterface

With #4251 `NodeType::getDefaultValuesForProperties` doesnt return a `DateTime` anymore for dateTime default values

Author: mhsdesign

Neos.ContentRepository.Core/Classes/Feature/NodeModification/Dto/SerializedPropertyValues.php

@@ -75,10 +75,6 @@ public static function defaultFromNodeType(NodeType $nodeType, PropertyConverter
     {
         $values = [];
         foreach ($nodeType->getDefaultValuesForProperties() as $propertyName => $defaultValue) {
-            if ($defaultValue instanceof \DateTimeInterface) {
-                $defaultValue = json_encode($defaultValue);
-            }
-
             $propertyType = PropertyType::fromNodeTypeDeclaration(
                 $nodeType->getPropertyType($propertyName),
                 PropertyName::fromString($propertyName),

Neos.ContentRepository.Core/Classes/NodeType/NodeType.php

@@ -433,7 +433,7 @@ public function getPropertyType(string $propertyName): string
      *
      * The default value is configured for each property under the "default" key.
      *
-     * @return array<string,mixed>
+     * @return array<string,int|float|string|bool|array<int|string,mixed>>
      * @api
      */
     public function getDefaultValuesForProperties(): array

Neos.ContentRepository.StructureAdjustment/src/Adjustment/PropertyAdjustment.php

@@ -77,9 +77,6 @@ public function findAdjustmentsForNodeType(NodeTypeName $nodeTypeName): \Generat
 
                 // detect missing default values
                 foreach ($nodeType->getDefaultValuesForProperties() as $propertyKey => $defaultValue) {
-                    if ($defaultValue instanceof \DateTimeInterface) {
-                        $defaultValue = json_encode($defaultValue);
-                    }
                     if (!array_key_exists($propertyKey, $propertyKeysInNode)) {
                         yield StructureAdjustment::createForNode(
                             $node,