kTemporalStructureMode4 is not used anywhere in the code. Bug: None Change-Id: I9a396f6706d26940fae68d1318942b5f31afa3bf Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/274380 Reviewed-by: Erik Språng <sprang@webrtc.org> Commit-Queue: Daniel.L (Byoungchan) Lee <daniel.l@hpcnt.com> Cr-Commit-Position: refs/heads/main@{#38079}