Remove H264 CHP field trial code.

Bug: webrtc:8317
Change-Id: I2da3cc6578dd8ff6e88052bc33cd38cb92af46dc
Reviewed-on: https://webrtc-review.googlesource.com/73242
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23077}

examples/objc/AppRTCMobile/ios/ARDAppDelegate.m

@@ -25,9 +25,7 @@
 
 - (BOOL)application:(UIApplication *)application
     didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
-  NSDictionary *fieldTrials = @{
-    kRTCFieldTrialH264HighProfileKey: kRTCFieldTrialEnabledValue,
-  };
+  NSDictionary *fieldTrials = @{};
   RTCInitFieldTrialDictionary(fieldTrials);
   RTCInitializeSSL();
   RTCSetupInternalTracer();