Update unit tests to follow video_rtp_depacketizer_h264's behavior of
setting is_first_packet_in_frame. This flag might be used to determine
if a frame can be assembled.
Bug: webrtc:384391181
Change-Id: I6750c20056e426e12c1d4e21eea4c641def7cfbd
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/373168
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Sergey Silkin <ssilkin@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43669}
a23fbc694f