HTTPCORE-774: fixed a race condition caused by concurrent update of the connection input window to the max value.

(cherry picked from commit d31d000)

Author: ok2c

httpcore5-h2/src/main/java/org/apache/hc/core5/http2/impl/nio/AbstractH2StreamMultiplexer.java

@@ -1621,7 +1621,6 @@ public void push(final List<Header> headers, final AsyncPushProducer pushProduce
 
         @Override
         public void update(final int increment) throws IOException {
-            incrementInputCapacity(0, connInputWindow, increment);
             incrementInputCapacity(id, inputWindow, increment);
         }