Revert "NetEq: Deprecate playout modes Fax, Off and Streaming"

This reverts commit 80c4cca4915dbc6094a5bfae749f85f7371eadd1.

Reason for revert: Breaks downstream tests.

Original change's description:
> NetEq: Deprecate playout modes Fax, Off and Streaming
> 
> The playout modes other than Normal have not been reachable for a long
> time, other than through tests. It is time to deprecate them.
> 
> The only meaningful use was that Fax mode was sometimes set from
> tests, in order to avoid time-stretching operations (accelerate and
> pre-emptive expand) from messing with the test results. With this CL,
> a new config is added instead, which lets the user specify exactly
> this: don't do time-stretching.
> 
> As a result of Fax and Off modes being removed, the following code
> clean-up was done:
> - Fold DecisionLogicNormal into DecisionLogic.
> - Remove AudioRepetition and AlternativePlc operations, since they can
>   no longer be reached.
> 
> Bug: webrtc:9421
> Change-Id: I651458e9c1931a99f3b07e242817d303bac119df
> Reviewed-on: https://webrtc-review.googlesource.com/84123
> Commit-Queue: Henrik Lundin <henrik.lundin@webrtc.org>
> Reviewed-by: Ivo Creusen <ivoc@webrtc.org>
> Reviewed-by: Minyue Li <minyue@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#23704}

TBR=henrik.lundin@webrtc.org,ivoc@webrtc.org,minyue@webrtc.org

Change-Id: I555aae8850fc4ac1ea919bfa72c11b5218066f30
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:9421
Reviewed-on: https://webrtc-review.googlesource.com/84680
Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org>
Commit-Queue: Henrik Lundin <henrik.lundin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23706}
diff --git a/modules/audio_coding/acm2/acm_receiver_unittest.cc b/modules/audio_coding/acm2/acm_receiver_unittest.cc
index 457ea1d..d1cff23 100644
--- a/modules/audio_coding/acm2/acm_receiver_unittest.cc
+++ b/modules/audio_coding/acm2/acm_receiver_unittest.cc
@@ -292,7 +292,7 @@
 class AcmReceiverTestFaxModeOldApi : public AcmReceiverTestOldApi {
  protected:
   AcmReceiverTestFaxModeOldApi() {
-    config_.neteq_config.for_test_no_time_stretching = true;
+    config_.neteq_config.playout_mode = kPlayoutFax;
   }
 
   void RunVerifyAudioFrame(RentACodec::CodecId codec_id) {
@@ -301,7 +301,7 @@
     // timestamp increments predictable; in normal mode, NetEq may decide to do
     // accelerate or pre-emptive expand operations after some time, offsetting
     // the timestamp.
-    EXPECT_TRUE(config_.neteq_config.for_test_no_time_stretching);
+    EXPECT_EQ(kPlayoutFax, config_.neteq_config.playout_mode);
 
     const RentACodec::CodecId kCodecId[] = {codec_id};
     AddSetOfCodecs(kCodecId);