rtmp2src: don't send window acknowledgement size commands twice

This causes servers such as AWS MediaLive to drop the connection, and
the message flow chart as documented in the "spec" always has the
server sending it first, and the client replying to it on reception of
the Set Peer Bandwidth, which we do since 286a3829b637.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/9360>

subprojects/gst-plugins-bad/gst/rtmp2/rtmp/rtmpclient.c

@@ -1438,9 +1438,6 @@ send_create_stream (GTask * task)
     gst_rtmp_connection_send_command (connection, NULL, NULL, 0,
         "FCPublish", command_object, stream_name, NULL);
   } else {
-    /* Matches librtmp */
-    gst_rtmp_connection_request_window_size (connection,
-        GST_RTMP_DEFAULT_WINDOW_ACK_SIZE);
     send_set_buffer_length (connection, 0, 300);
   }