Ensure monitoring/_bulk route is fully aggregated

This route still exists in the code even if it is two major version old.
We should still support it properly with our streaming changes.

modules/transport-netty4/src/main/java/org/elasticsearch/http/netty4/Netty4HttpServerTransport.java

@@ -374,7 +374,9 @@ protected HttpMessage createMessage(String[] initialLine) throws Exception {
             // combines the HTTP message pieces into a single full HTTP request (with headers and body)
             final HttpObjectAggregator aggregator = new Netty4HttpAggregator(
                 handlingSettings.maxContentLength(),
-                httpPreRequest -> enabled.get() == false || (httpPreRequest.rawPath().endsWith("/_bulk") == false)
+                httpPreRequest -> enabled.get() == false
+                    || ((httpPreRequest.rawPath().endsWith("/_bulk") == false)
+                        || httpPreRequest.rawPath().startsWith("/_xpack/monitoring/_bulk"))
             );
             aggregator.setMaxCumulationBufferComponents(transport.maxCompositeBufferComponents);
             ch.pipeline()