Never failover message sends.

SignalServiceKit/src/Messages/OWSMessageSender.m

@@ -1070,15 +1070,6 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
         OWSLogWarn(@"Sending a message with no device messages.");
     }
 
-    // NOTE: canFailoverUDAuth depends on whether or not we're sending a
-    // sync message because sync messages use different device lists
-    // for UD-auth and Non-UD-auth requests.
-    //
-    // Therefore, for sync messages, we can't use OWSRequestMaker's
-    // retry/failover logic; we need to use the message sender's retry
-    // logic that will build a new set of device messages.
-    BOOL isSyncMessageSend = messageSend.isLocalNumber;
-    BOOL canFailoverUDAuth = !isSyncMessageSend;
     OWSRequestMaker *requestMaker = [[OWSRequestMaker alloc] initWithLabel:@"Message Send"
         requestFactoryBlock:^(SMKUDAccessKey *_Nullable udAccessKey) {
             return [OWSRequestFactory submitMessageRequestWithRecipient:recipient.recipientId
@@ -1098,7 +1089,7 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
         }
         recipientId:recipient.recipientId
         udAccess:messageSend.udAccess
-        canFailoverUDAuth:canFailoverUDAuth];
+        canFailoverUDAuth:NO];
     [[requestMaker makeRequestObjc]
             .then(^(OWSRequestMakerResult *result) {
                 dispatch_async([OWSDispatch sendingQueue], ^{