Fine tune the IntelligibilityEnhancer

Label less chunks as speech, adapt slower and be more conservative with the maximum gain it can apply.

Review-Url: https://codereview.webrtc.org/2087623003
Cr-Commit-Position: refs/heads/master@{#13242}
diff --git a/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc b/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
index 3675f66..dfa912b 100644
--- a/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
+++ b/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
@@ -23,7 +23,7 @@
 namespace {
 
 const float kMinFactor = 0.01f;
-const float kMaxFactor = 1000.f;
+const float kMaxFactor = 100.f;
 
 // Return |current| changed towards |target|, with the relative change being at
 // most |limit|.