Http/2 - remove unused 'compressedData'

and thus reduce memory consumption, allocations etc.

Task-number: QTBUG-68394
Change-Id: Ibad9b01a1e709e6abafcd9531fbcfc1eafa9cff3
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/access/qhttp2protocolhandler.cpp

@@ -1150,7 +1150,6 @@ void QHttp2ProtocolHandler::updateStream(Stream &stream, const Frame &frame,
         auto &httpRequest = stream.request();
         auto replyPrivate = httpReply->d_func();
 
-        replyPrivate->compressedData.append(data, length);
         replyPrivate->totalProgress += length;
 
         const QByteArray wrapped(data, length);