Revert "obsolete the CT_PivotCacheDefinitionExtension complex type"

This reverts commit e7bca5d.

Author: mikeebowen

gen/DocumentFormat.OpenXml.Generator.Models/Generators/Elements/DataModelWriterExtensions.cs

@@ -20,7 +20,6 @@ public static class AttributeStrings
         public const string ObsoletePropertyError = "[Obsolete(\"Unused property, will be removed in a future version.\", true)]";
         public const string ObsoleteAttributeWarn = "[Obsolete(\"Unused attribute, will be removed in a future version.\", false)]";
         public const string ObsoleteAttributeError = "[Obsolete(\"Unused attribute, will be removed in a future version.\", true)]";
-        public const string ObsoleteChildWarn = "[Obsolete(\"Obsolete child element, will be removed in a future version.\", false)]";
         public const string EditorBrowsableAlways = "[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Always)] ";
         public const string EditorBrowsableAdvanced = "[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Advanced)] ";
         public const string EditorBrowsableNever = "[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)] ";
@@ -38,12 +37,6 @@ public static class AttributeStrings
         AttributeStrings.EditorBrowsableNever,
     ];
 
-    private static readonly List<string> ObsoleteChildWarnList =
-    [
-        AttributeStrings.ObsoleteChildWarn,
-        AttributeStrings.EditorBrowsableNever,
-    ];
-
     // Use this dictionary to add attributes like ObsoleteAttribute or other directives to classes, child elements or attributes.
     private static readonly Dictionary<TypedQName, Dictionary<TypedQName, List<string>>> _attributeData =
         new Dictionary<TypedQName, Dictionary<TypedQName, List<string>>>()
@@ -151,16 +144,6 @@ public static class AttributeStrings
                     },
                 }
             },
-            {
-                "x:CT_PivotCacheDefinitionExtension/x:ext",
-                new Dictionary<TypedQName, List<string>>()
-                {
-                    {
-                        "xprd:CT_PivotCacheRichInfo/xprd:richInfo",
-                        ObsoleteChildWarnList
-                    },
-                }
-            },
         };
 
     public static bool GetDataModelSyntax(this IndentedTextWriter writer, OpenXmlGeneratorServices services, SchemaNamespace model)