BUGFIX: Remove default value for subtreetags to fix MySQL support

Fixes: #5252

Neos.ContentGraph.DoctrineDbalAdapter/src/DoctrineDbalContentGraphSchemaBuilder.php

@@ -70,7 +70,7 @@ private function createHierarchyRelationTable(): Table
  DbalSchemaFactory::columnForDimensionSpacePointHash('dimensionspacepointhash')->setNotnull(true),
  DbalSchemaFactory::columnForNodeAnchorPoint('parentnodeanchor'),
  DbalSchemaFactory::columnForNodeAnchorPoint('childnodeanchor'),
- (new Column('subtreetags', self::type(Types::JSON)))->setDefault('{}'),
+ (new Column('subtreetags', self::type(Types::JSON))),
  ]);
 
  return $table