Delay the call to QNetworkConfigurationManagerPrivate::updateConfigurations

We are running a system on a server and would like to disable the bearer handling completely but sadly when creating a QNAM the QNetworkConfigManager will load the bearer plugin and start to poll.

It would be nice if the call to initialize could be delayed to the point it is first used or to disable the bearer plugins at runtime. Right now we would have to resort to removing the plugins.