Remove nesting of Naggy/Strict/NiceMock

This will soon become a compile-time error. Fix class hierarchies that
wrap StrictMock in a NiceMock or vice-versa by removing redundant
wrappings and removing inheritance from Nice/StrictMock and fixing the
call sites as appropriate.

Bug: b/173702213
Change-Id: Ic90b1f270c180f7308f40e52e358a8f6a6baad86
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/196461
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32783}

modules/audio_processing/include/mock_audio_processing.h

@@ -67,7 +67,7 @@ class MockEchoControl : public EchoControl {
   MOCK_METHOD(bool, ActiveProcessing, (), (const, override));
 };
 
-class MockAudioProcessing : public ::testing::NiceMock<AudioProcessing> {
+class MockAudioProcessing : public AudioProcessing {
  public:
   MockAudioProcessing() {}