stop clobbering cookies, ASP.NET/OWIN

happier-authentication.cs

public void ConfigureAuth(IAppBuilder app)
{
    app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType);

    app.UseCookieAuthentication(new CookieAuthenticationOptions
    {
        CookieManager = new SystemWebChunkingCookieManager()
    });
    
    var authenticationOptions = new OpenIdConnectAuthenticationNotifications();
    app.UseOpenIdConnectAuthentication(authenticationOptions);
}