[m125] webrtc stats: fix video remote-outbound-rtp timestamp

which had a 70 year offset (i.e. 2094 instead of 2024) which broke
the webrtc-internal stats graphs. A similar adjustment is done
for audio in audio/channel_receive.cc

BUG=webrtc:12529,chromium:336222282

(cherry picked from commit 77313800c72fa1e33c30e952800e4157e9ad44a4)

Change-Id: I0ce43cc8b451185bc056cf9e54757ef22d006c99
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/347780
Reviewed-by: Florent Castelli <[email protected]>
Commit-Queue: Philipp Hancke <[email protected]>
Reviewed-by: Harald Alvestrand <[email protected]>
Cr-Original-Commit-Position: refs/heads/main@{#42114}
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/348702
Commit-Queue: Harald Alvestrand <[email protected]>
Cr-Commit-Position: refs/branch-heads/6422@{webrtc-sdk#1}
Cr-Branched-From: b831eb8-refs/heads/main@{#42072}

video/video_receive_stream2.cc

@@ -573,9 +573,10 @@ VideoReceiveStreamInterface::Stats VideoReceiveStream2::GetStats() const {
       rtp_video_stream_receiver_.GetSenderReportStats();
   if (rtcp_sr_stats) {
     stats.last_sender_report_timestamp_ms =
-        rtcp_sr_stats->last_arrival_timestamp.ToMs();
+        rtcp_sr_stats->last_arrival_timestamp.ToMs() -
+        rtc::kNtpJan1970Millisecs;
     stats.last_sender_report_remote_timestamp_ms =
-        rtcp_sr_stats->last_remote_timestamp.ToMs();
+        rtcp_sr_stats->last_remote_timestamp.ToMs() - rtc::kNtpJan1970Millisecs;
     stats.sender_reports_packets_sent = rtcp_sr_stats->packets_sent;
     stats.sender_reports_bytes_sent = rtcp_sr_stats->bytes_sent;
     stats.sender_reports_reports_count = rtcp_sr_stats->reports_count;