Since b76d336549
pads are deactivated when going to READY but in `uridecodebin(3)`, the
sources source pads are activated while in NULL state (when PULL mode is
supported), meaning that we are ending up deactivating those pads in
NULL_TO_READY, breaking the pipeline.
The intent of the commit mentioned above is to ensure that the pads are
deactivated either in PAUSED_TO_READY or READY_TO_READY, so it should
be safe to avoid deactivating in NULL_TO_READY.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3849>
1bab0ef2aa