[IndexPatterns] Clean up StubIndexPattern (#108555)

Author: Dosant

docs/development/plugins/data/public/kibana-plugin-plugins-data-public.indexpatternattributes.type.md

@@ -7,5 +7,5 @@
 <b>Signature:</b>
 
 ```typescript
-type: string;
+type?: string;
 ```

docs/development/plugins/data/public/kibana-plugin-plugins-data-public.indexpatternattributes.typemeta.md

@@ -7,5 +7,5 @@
 <b>Signature:</b>
 
 ```typescript
-typeMeta: string;
+typeMeta?: string;
 ```

docs/development/plugins/data/server/kibana-plugin-plugins-data-server.indexpatternattributes.type.md

@@ -7,5 +7,5 @@
 <b>Signature:</b>
 
 ```typescript
-type: string;
+type?: string;
 ```

docs/development/plugins/data/server/kibana-plugin-plugins-data-server.indexpatternattributes.typemeta.md

@@ -7,5 +7,5 @@
 <b>Signature:</b>
 
 ```typescript
-typeMeta: string;
+typeMeta?: string;
 ```