Inverted if condition in StreamWrapper.DisposeAsync

[MihaZupan]

Just spotted while reading code, not sure if it's currently being used anywhere.

grpc-dotnet/src/Grpc.Net.Client/Balancer/Internal/StreamWrapper.cs

Lines 106 to 112 in f4148e8

	// Avoid invoking dispose callback multiple times.
	if (_disposed)
	{
	_onDispose(this);
	await _inner.DisposeAsync().ConfigureAwait(false);
	_disposed = true;
	}