Add missing field-trial in Vp9EncoderReferencesFuzzer

Bug: chromium:371233788
Change-Id: I763ce26f17c7d931fef17025f0634c55cbb70551
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/365541
Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43236}
diff --git a/test/fuzzers/vp9_encoder_references_fuzzer.cc b/test/fuzzers/vp9_encoder_references_fuzzer.cc
index c39b896..88c0d43 100644
--- a/test/fuzzers/vp9_encoder_references_fuzzer.cc
+++ b/test/fuzzers/vp9_encoder_references_fuzzer.cc
@@ -209,7 +209,8 @@
         key == "WebRTC-VP9-GetEncoderInfoOverride" ||
         key == "WebRTC-VP9-PerformanceFlags" ||
         key == "WebRTC-VP9QualityScaler" ||
-        key == "WebRTC-VP9-SvcForSimulcast") {
+        key == "WebRTC-VP9-SvcForSimulcast" ||
+        key == "WebRTC-StableTargetRate") {
       return "";
     }