Update buffer limit when peeking large box header in `HeifSniffer`

When sniffing a large HEIF/MP4 box where
`atomSize == DEFINES_LARGE_SIZE`, `buffer.limit` needs to be updated
to `LONG_HEADER_SIZE` before reading the 64-bit atom size.

Also enable `ParsableByteArray` limit enforcement in
`HeifExtractorTest`, `MotionPhotoPlaybackTest`, and
`MetadataRetrieverTest` to prevent backsliding.

PiperOrigin-RevId: 937228876