Remove deprecated unit test helper functions CallPreProcessAudioBuffer()
and CallPreProcForChangingAudio(). Replace the use of these functions
with CallAgcSequence(). Remove a duplicate unit test using one of these
functions. The new calls follow the API contract.
Bug: webrtc:7494
Change-Id: Idc033cb48f4fab1814c4c6e0f23edc4a6a9faa64
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/285960
Reviewed-by: Alessio Bazzica <alessiob@webrtc.org>
Commit-Queue: Hanna Silen <silen@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38826}