Fix failing HttpEndtoEndTest (#835)

Author: joannatk

proxy/src/test/java/com/wavefront/agent/HttpEndToEndTest.java

@@ -897,6 +897,9 @@ protected void handleHttpMessage(ChannelHandlerContext ctx, FullHttpRequest requ
       } else if (path.endsWith("/wfproxy/saveConfig")) {
         writeHttpResponse(ctx, HttpResponseStatus.OK, "", request);
         return;
+      } else if (path.endsWith("/wfproxy/savePreprocessorRules")) {
+        writeHttpResponse(ctx, HttpResponseStatus.OK, "", request);
+        return;
       }
       HttpResponse response = func.apply(request);
       logger.fine("Responding with HTTP " + response.status());