This causes a lot of nasty side effects (like decoders assuming they are
actually linked downstream).
The reason why this was done was to check whether a decoder could handle the
actual caps, but this is the wrong way to do it.
The proper way to query whether a decoder can handle certain caps is via
`GST_QUERY_ACCEPT_CAPS` which is already done just before.
Partially reverts !4677 and partially fixes#3160
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5821>
2d57bec920