Modify unit tests ahead of changes that will replace the minimum digital gain with a fixed value 0 and always enable digital gain compensation. Bug: webrtc:7494 Change-Id: I9df95667b831d5b68e70aaba22f631b398edf8e2 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/280960 Commit-Queue: Hanna Silen <silen@webrtc.org> Reviewed-by: Alessio Bazzica <alessiob@webrtc.org> Cr-Commit-Position: refs/heads/main@{#38553}