Remove remnants of deprecated field trial strings

Bug: webrtc:9734
Change-Id: Ifceeb9b0d7da924544be114120129e0c1ff5cde9
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/293345
Reviewed-by: Emil Lundmark <lndmrk@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39309}

test/fuzzers/vp9_encoder_references_fuzzer.cc

diff --git a/test/fuzzers/vp9_encoder_references_fuzzer.cc b/test/fuzzers/vp9_encoder_references_fuzzer.cc
index 09848ae..7503507 100644
--- a/test/fuzzers/vp9_encoder_references_fuzzer.cc
+++ b/test/fuzzers/vp9_encoder_references_fuzzer.cc
@@ -186,8 +186,6 @@
     // Ignore following field trials.
     if (key == "WebRTC-CongestionWindow" ||
         key == "WebRTC-UseBaseHeavyVP8TL3RateAllocation" ||
-        key == "WebRTC-SimulcastUpswitchHysteresisPercent" ||
-        key == "WebRTC-SimulcastScreenshareUpswitchHysteresisPercent" ||
         key == "WebRTC-VideoRateControl" ||
         key == "WebRTC-VP9-PerformanceFlags" ||
         key == "WebRTC-VP9VariableFramerateScreenshare" ||