Updated Function Score Query Test with Explain Fixes for 8.15.1 (elas…

…tic#111929)

* updated test for 8.15.1

* Update docs/changelog/111929.yaml

* Delete docs/changelog/111929.yaml

plugins/examples/script-expert-scoring/src/yamlRestTest/resources/rest-api-spec/test/script_expert_scoring/20_score.yml

@@ -55,7 +55,7 @@ setup:
 "document scoring with custom explanation":
 
   - requires:
-      cluster_features: [ "gte_v8.16.0" ]
+      cluster_features: [ "gte_v8.15.1" ]
       reason: "bug fixed where explanations were throwing npe prior to 8.16"
 
   - do: