Support explicit null chunking_settings in semantic_text field mappings

Author: kderusso

output/schema/schema.json

@@ -264,7 +264,7 @@ export class SemanticTextProperty {
    * chunking settings sent in the inference endpoint associated with inference_id. If chunking settings are updated,
    * they will not be applied to existing documents until they are reindexed.
    */
-  chunking_settings?: ChunkingSettings
+  chunking_settings?: ChunkingSettings | null
   /**
    * Multi-fields allow the same string value to be indexed in multiple ways for different purposes, such as one
    * field for search and a multi-field for sorting and aggregations, or the same string value analyzed by different analyzers.