Only used in unit tests and a duplication of what `capture_output_rms_` already does. This CL also removes `AudioProcessingStats::output_rms_dbfs`, which is now unused. Bug: webrtc:5298 Fix: chromium:1261339 Change-Id: I6e583c11d4abb58444c440509a8495a7f5ebc589 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/235664 Reviewed-by: Sam Zackrisson <saza@webrtc.org> Commit-Queue: Alessio Bazzica <alessiob@webrtc.org> Cr-Commit-Position: refs/heads/main@{#35246}