Ensures the residual echo detector does not requiring band-splitting

This CL removes the residual echo detector from the list of
modules in APM that requires band-splitting.

BUG=webrtc:6220, webrtc:6183

Review-Url: https://codereview.webrtc.org/2884913002
Cr-Commit-Position: refs/heads/master@{#18164}
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.cc b/webrtc/modules/audio_processing/audio_processing_impl.cc
index 900a8ec..756cc0c 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.cc
+++ b/webrtc/modules/audio_processing/audio_processing_impl.cc
@@ -220,11 +220,9 @@
     const {
 #if WEBRTC_INTELLIGIBILITY_ENHANCER
   return CaptureMultiBandProcessingActive() ||
-         intelligibility_enhancer_enabled_ ||
-         voice_activity_detector_enabled_ || residual_echo_detector_enabled_;
+         intelligibility_enhancer_enabled_ || voice_activity_detector_enabled_;
 #else
-  return CaptureMultiBandProcessingActive() ||
-         voice_activity_detector_enabled_ || residual_echo_detector_enabled_;
+  return CaptureMultiBandProcessingActive() || voice_activity_detector_enabled_;
 #endif
 }
 
@@ -240,7 +238,7 @@
     const {
   return RenderMultiBandProcessingActive() || echo_canceller_enabled_ ||
          mobile_echo_controller_enabled_ || adaptive_gain_controller_enabled_ ||
-         residual_echo_detector_enabled_ || echo_canceller3_enabled_;
+         echo_canceller3_enabled_;
 }
 
 bool AudioProcessingImpl::ApmSubmoduleStates::RenderMultiBandProcessingActive()