Shorten the fir filter adapt test quite a bit.

The test is likely timing out on iOS simulator (see bug). Maybe I'm
going a bit overboard here :) if you want to keep all the cases I
removed, you can run some cases in one test method and the others in
another test method. Are the cases I removed particularly important?

Bug: webrtc:11284
Change-Id: I8f2e8830f931594c3471d1c20a2654e258b9fcf0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/166169
Reviewed-by: Per Åhgren <peah@webrtc.org>
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30277}
diff --git a/modules/audio_processing/aec3/adaptive_fir_filter_unittest.cc b/modules/audio_processing/aec3/adaptive_fir_filter_unittest.cc
index e99ff2a..9c48a43 100644
--- a/modules/audio_processing/aec3/adaptive_fir_filter_unittest.cc
+++ b/modules/audio_processing/aec3/adaptive_fir_filter_unittest.cc
@@ -330,8 +330,8 @@
   constexpr size_t kNumBands = NumBandsForRate(kSampleRateHz);
   constexpr size_t kNumBlocksToProcessPerRenderChannel = 1000;
 
-  for (size_t num_capture_channels : {1, 2, 4}) {
-    for (size_t num_render_channels : {1, 2, 3, 6, 8}) {
+  for (size_t num_capture_channels : {1, 4}) {
+    for (size_t num_render_channels : {1, 8}) {
       ApmDataDumper data_dumper(42);
       EchoCanceller3Config config;