HTTP/2 shutdown cleanup miss

Motiviation:
https://github.com/netty/netty/pull/3865 was merged from a machine with old code. A test case that was updates was not merged.

Modifications:
- Merge the missing test case updates

Result:
Test case no longer fails.

codec-http2/src/test/java/io/netty/handler/codec/http2/Http2ConnectionHandlerTest.java

@@ -319,6 +319,9 @@ public class Http2ConnectionHandlerTest {
             }
         }).when(future).addListener(any(GenericFutureListener.class));
         handler.close(ctx, promise);
+        if (future.isDone()) {
+            when(connection.numActiveStreams()).thenReturn(0);
+        }
         handler.closeStream(stream, future);
         // Simulate another stream close call being made after the context should already be closed.
         handler.closeStream(stream, future);