Remove extra line from end (#10673)

Motivation:
`Http2MultiplexHandler` have to 2 empty lines at the end instead of 1.

Modification:
Removed 1 extra line.

Result:
Little better code style.

codec-http2/src/main/java/io/netty/handler/codec/http2/Http2MultiplexHandler.java

@@ -354,4 +354,3 @@ public final class Http2MultiplexHandler extends Http2ChannelDuplexHandler {
         }
     }
 }
-