[ML] Mute semantic_search YAML test (#90905)

Relates #90904

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/ml/semantic_search.yml

@@ -110,6 +110,10 @@ setup:
 
 ---
 "Test semantic search":
+  - skip:
+      reason: "https://github.com/elastic/elasticsearch/issues/90904"
+      version: "8.6.0 - "
+
   - do:
       ml.start_trained_model_deployment:
         model_id: text_embedding_model