fix: revert changes in HttpJsonClientCalls

Author: diegomarquezp

sdk-platform-java/gax-java/gax-httpjson/src/main/java/com/google/api/gax/httpjson/HttpJsonClientCalls.java

@@ -76,10 +76,8 @@ public static <RequestT, ResponseT> HttpJsonClientCall<RequestT, ResponseT> newC
     // if the Universe Domain is valid.
     httpJsonContext.validateUniverseDomain();
 
-    HttpJsonCallOptions callOptions = httpJsonContext.getCallOptions();
-
     // TODO: add headers interceptor logic
-    return httpJsonContext.getChannel().newCall(methodDescriptor, callOptions);
+    return httpJsonContext.getChannel().newCall(methodDescriptor, httpJsonContext.getCallOptions());
   }
 
   static <RequestT, ResponseT> ApiFuture<ResponseT> futureUnaryCall(