AEC3: Ensure that the high-pass filter is on whenever the AEC is active

This CL ensures that the high-pass filter is on whenever the echo
controller is on. This is important as the echo controller code assumes
that the external high-pass filter is active.

The CL also corrects the ToggleAec unit test (which started failing
after this code change).

Bug: webrtc:11159, chromium:1030179
Change-Id: Ief86eda8f7c67df1c25ac1a06d2cc0778e01196d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/161228
Commit-Queue: Per Åhgren <peah@webrtc.org>
Reviewed-by: Sam Zackrisson <saza@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29998}
diff --git a/modules/audio_processing/test/debug_dump_test.cc b/modules/audio_processing/test/debug_dump_test.cc
index b769a66..9561091 100644
--- a/modules/audio_processing/test/debug_dump_test.cc
+++ b/modules/audio_processing/test/debug_dump_test.cc
@@ -346,7 +346,7 @@
   generator.StartRecording();
   generator.Process(100);
 
-  apm_config.echo_canceller.enabled = true;
+  apm_config.echo_canceller.enabled = false;
   generator.apm()->ApplyConfig(apm_config);
 
   generator.Process(100);