When updating a manifest during live playback, preserve the current representation for each stream. During update_fragment_info, if the current representation changed because it couldn't be matched, trigger a caps change and new header download. This reverts commit e0e1db212f and reapplies "dashdemux: Fix issue when manifest update sets slow start without passing necessary header & caps changes downstream" with changes. Fixes https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/issues/507 Fixes https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/issues/1729 Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2920>
e0e1db212f