webrtc: add two newly implemented stats to allowlist

BUG=webrtc:14022

Change-Id: I0902335d3039fd6b4c53aa9cdccdc0c6827b8247
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3627544


Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
Reviewed-by: Harald Alvestrand <hta@chromium.org>
Cr-Commit-Position: refs/heads/main@{#999813}