decodebin(3) runs a scheduling query before pads are activated which ultimately triggers basesrc->start which will automatically call `gst_base_src_start_complete` for any source that is not marked as 'async'. This calls will harmlessly bail out in `not_activated_yet` so we should not warn in that case. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6011>