Make field trial string enable_retransmit_all_layers enabled by default.

Bug: webrtc:14959
Change-Id: I850c3ca28fdfc639d2335199ab1f17884029e19d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/317580
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Commit-Queue: Ying Wang <yinwa@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40622}
diff --git a/call/rtp_video_sender.cc b/call/rtp_video_sender.cc
index b7616d1..de50f7c 100644
--- a/call/rtp_video_sender.cc
+++ b/call/rtp_video_sender.cc
@@ -280,7 +280,7 @@
         crypto_options.sframe.require_frame_encryption;
     video_config.field_trials = &trials;
     video_config.enable_retransmit_all_layers =
-        video_config.field_trials->IsEnabled(
+        !video_config.field_trials->IsDisabled(
             "WebRTC-Video-EnableRetransmitAllLayers");
 
     const bool using_flexfec =