Revert "h264: fix first_packet_in_frame logic for multislice in a single rtp packet"

This reverts commit 3753c8190e3f0aca6758a5521e33f8b5d4f09ab4.

Reason for revert: Break assembling of hardware encoded h264 P frame on
weak network condition.

Original change's description:
> h264: fix first_packet_in_frame logic for multislice in a single rtp packet
>
> a frame must be (or should be) first when it contains either SPS (but not just PPS),
> is an IDR or is a slice with first_mb_in_slice == 0.
>
> Fixes an edge case where a STAP-A with SPS, PPS and multiple slices of an IDR fit
> into a single RTP packet which can happen with small 320x196 frames
>
> BUG=webrtc:352379280,webrtc:346608838
>
> Change-Id: Ic6dea6c81db759d0d7ddd4054407103fd791f6c5
> No-Try: true
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/357121
> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
> Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
> Reviewed-by: Sergey Silkin <ssilkin@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#42652}

Bug: webrtc:368335257
Change-Id: I07725c78be628bff71b79b8b9369677e39f5f5ac
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/363080
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Sergey Silkin <ssilkin@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Philipp Hancke <phancke@meta.com>
Cr-Commit-Position: refs/heads/main@{#43062}
diff --git a/AUTHORS b/AUTHORS
index 971987d..d46a592 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -53,6 +53,7 @@
 Eric Rescorla, RTFM Inc. <ekr@rtfm.com>
 Filip Hlasek <filip@orcamobility.ai>
 Frederik Riedel, Frogg GmbH <frederik.riedel@frogg.io>
+Gao Chun <gaochun.dev@gmail.com>
 Giji Gangadharan <giji.g@samsung.com>
 Graham Yoakum <gyoakum@skobalt.com>
 Gustavo Garcia <gustavogb@gmail.com>