Remove intermediate 429 response close from retry loop

This fix belongs in a separate PR since it's independent of the
configurable max backoff feature.

Author: jeffreyparker

duo-client/src/main/java/com/duosecurity/client/Http.java

@@ -319,10 +319,6 @@ private Response executeRequest(Request request) throws Exception {
         return response;
       }
 
-      // Close the 429 response to release the connection back to the pool before retrying
-      if (response.body() != null) {
-        response.close();
-      }
       sleep(backoffMs + nextRandomInt(1000));
       backoffMs *= BACKOFF_FACTOR;
     }