Previous computation assumed that local clock is UTC. It isn't. Adding integration test for abs-capture stats. Bug: webrtc:380712819 Change-Id: I054d61984cbd017b7ad04ab13e5a687eab89db69 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/369421 Commit-Queue: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Johannes Kron <kron@webrtc.org> Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org> Cr-Commit-Position: refs/heads/main@{#43465}