adapt tests

Author: jimczi

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

@@ -86,7 +86,7 @@ setup:
 "Highlighting empty index":
   - do:
       search:
-        index: test-sparse-index
+        index: test-dense-index
         body:
           query:
             match_all: {}

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

@@ -58,6 +58,25 @@ setup:
               body:
                 type: semantic_text
                 inference_id: dense-inference-id
+              another_body:
+                type: semantic_text
+                inference_id: dense-inference-id
+
+---
+"Highlighting empty index":
+  - do:
+      search:
+        index: test-dense-index
+        body:
+          query:
+            match_all: {}
+          highlight:
+            fields:
+              another_body: {}
+
+  - match:      { hits.total.value: 1 }
+  - match:      { hits.hits.0._id: "doc_1" }
+  - not_exists:   hits.hits.0.highlight.another_body
 
 ---
 "Highlighting using a sparse embedding model":