Fix test

Author: carlosdelest

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/DenseVectorFieldTypeIT.java

@@ -84,7 +84,7 @@ public DenseVectorFieldTypeIT(
         @Name("synthetic") boolean synthetic
     ) {
         this.elementType = elementType;
-        this.similarity = similarity == null ? null : similarity;
+        this.similarity = similarity;
         this.index = index;
         this.synthetic = synthetic;
     }