Add GOP N=1 to post-capture mediaconch policy check for FFV1 files

[iamdamosuzuki]

we should do this to make sure the MP4 GOP size isn't contaminating the FFV1 files.

[privatezero]

Looks like that check is already in there: https://github.com/amiaopensource/vrecord/blob/main/vrecord#L2611. Was it not working?