Blocking on polling operations prevents OAuth from working in Streaming scenarios

[stevengum]

SDK Version: 4.10.x

In the 4.10.0 release the team cleaned up the code base which resulted in some background tasks being waited on. The default number of tasks and interval between each task results in dropped streaming connections due to timeouts. Bots will wait for the operations to complete and then finish its response to the channel.

botbuilder-dotnet/libraries/Microsoft.Bot.Builder/TokenResolver.cs

Lines 47 to 48 in 31af94b

	// Wait for all the poll operations to complete.
	Task.WaitAll(pollTokenTasks.ToArray());

These polling operations should not block, as they simulate the normal OOB HTTP OAuth flows (a TokenResponse Event activity is sent from the token service to the bot).