Update multi-field name to subfield_keyword

Author: parkertimmins

server/src/test/java/org/elasticsearch/index/mapper/blockloader/TextFieldBlockLoaderTests.java

@@ -41,7 +41,7 @@ public static Object expectedValue(Map<String, Object> fieldMapping, Object valu
 
         var fields = (Map<String, Object>) fieldMapping.get("fields");
         if (fields != null) {
-            var keywordMultiFieldMapping = (Map<String, Object>) fields.get("kwd");
+            var keywordMultiFieldMapping = (Map<String, Object>) fields.get("subfield_keyword");
             Object normalizer = fields.get("normalizer");
             boolean docValues = hasDocValues(keywordMultiFieldMapping, true);
             boolean store = keywordMultiFieldMapping.getOrDefault("store", false).equals(true);