Apply code review suggestions.

Author: afoucret

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/elastic/completion/ElasticInferenceServiceCompletionModel.java

@@ -61,8 +61,8 @@ public ElasticInferenceServiceCompletionModel(
         TaskType taskType,
         String service,
         ElasticInferenceServiceCompletionServiceSettings serviceSettings,
-        TaskSettings taskSettings,
-        SecretSettings secretSettings,
+        @Nullable TaskSettings taskSettings,
+        @Nullable SecretSettings secretSettings,
         ElasticInferenceServiceComponents elasticInferenceServiceComponents
     ) {
         super(
@@ -79,7 +79,7 @@ public ElasticInferenceServiceCompletionModel(
         ElasticInferenceServiceCompletionServiceSettings serviceSettings
     ) {
         super(model, serviceSettings);
-        this.uri = model.uri;
+        this.uri = createUri();
     }
 
     @Override