Revert "avcodec/decode: copy the output parameters from the last bsf in the chain back to the AVCodecContext"

This reverts commit f631c328.

The avcodec_parameters_to_context() call was freeing and reallocating
AVCodecContext->extradata, essentially taking ownership of it, which according
to the doxy is user owned. This is an API break and has produced crashes in
some library users like Firefox[1].

Revert until a better solution is found to internally propagate the filtered
extradata back into the decoder context, or a decision is made to change the
API.

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1486080Signed-off-by: James Almer <jamrial@gmail.com>