Fast Seek can lose the decode in AV1 WebM

Enabling fast seek (--input-fast-seek) with this file https://sjeng.org/ftp/work/SVTAV1-G300-F24.webm and seeking many times ends up with no video update.

We may be feeding bad data to dav1d as it errors with dav1d decoder error: Decoder feed error -22! On 4.0 there is no such message but the result is the same.

After that it doesn't recover.

Issue originally reported at https://github.com/AOMediaCodec/SVT-AV1/issues/1667

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