fix test

Author: jimczi

x-pack/plugin/inference/src/yamlRestTest/resources/rest-api-spec/test/inference/90_semantic_text_highlighter.yml

@@ -83,7 +83,7 @@ setup:
         refresh: true
 
 ---
-"Highlighting empty index":
+"Highlighting empty field":
   - do:
       search:
         index: test-dense-index

x-pack/plugin/inference/src/yamlRestTest/resources/rest-api-spec/test/inference/90_semantic_text_highlighter_bwc.yml

@@ -63,7 +63,17 @@ setup:
                 inference_id: dense-inference-id
 
 ---
-"Highlighting empty index":
+"Highlighting empty field":
+  - do:
+        index:
+          index: test-dense-index
+          id: doc_1
+          body:
+            body: [ "ElasticSearch is an open source, distributed, RESTful, search engine which is built on top of Lucene internally and enjoys all the features it provides.", "You Know, for Search!" ]
+          refresh: true
+
+  - match: { result: created }
+
   - do:
       search:
         index: test-dense-index