Use function_video_(en|de)coder_factory from api

Remove them from test.
It is completion of the move started with
https://webrtc-review.googlesource.com/c/src/+/107705

Bug: None
Change-Id: Ib0b26db04a1ee814322851280ba1e59b4b3f7ce6
Reviewed-on: https://webrtc-review.googlesource.com/c/107891
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25392}
diff --git a/test/fake_vp8_encoder_unittest.cc b/test/fake_vp8_encoder_unittest.cc
index d881edc..4e576fe 100644
--- a/test/fake_vp8_encoder_unittest.cc
+++ b/test/fake_vp8_encoder_unittest.cc
@@ -14,11 +14,11 @@
 #include "absl/memory/memory.h"
 #include "api/test/create_simulcast_test_fixture.h"
 #include "api/test/simulcast_test_fixture.h"
+#include "api/test/video/function_video_decoder_factory.h"
+#include "api/test/video/function_video_encoder_factory.h"
 #include "modules/video_coding/utility/simulcast_test_fixture_impl.h"
 #include "test/fake_vp8_decoder.h"
 #include "test/fake_vp8_encoder.h"
-#include "test/function_video_decoder_factory.h"
-#include "test/function_video_encoder_factory.h"
 
 namespace webrtc {
 namespace test {