AEC3: No ERLE uncertainty with diverged filter

Disable the use of ERLE uncertainty with a diverged filter as it has
been shown to make transparency worse.

Bug: webrtc:9668
Change-Id: I5e23665def187c0d1cf47a029c4ebc950e79bb44
Reviewed-on: https://webrtc-review.googlesource.com/96140
Reviewed-by: Per Åhgren <peah@webrtc.org>
Commit-Queue: Gustaf Ullberg <gustaf@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24446}

modules/audio_processing/aec3/aec_state.h

@@ -74,10 +74,6 @@ class AecState {
 
   // Returns any uncertainty in the ERLE estimate.
   absl::optional<float> ErleUncertainty() const {
-    if (allow_linear_mode_with_diverged_filter_ && diverged_linear_filter_) {
-      return 10.f;
-    }
-
     if (!filter_has_had_time_to_converge_ &&
         use_uncertainty_until_sufficiently_adapted_) {
       return uncertainty_before_convergence_;