[collector] add back the logging exporter temporarily

[TylerHelmuth]

I realized that when we removed the logging exporter that we broke anyone who was relying on the default configuration when they included it in an exporters list. It is extremely common to add an exporter when using the chart - when people configure the exporters list with the new exporter AND the logging exporter, an upgrade to the latest chart would fail.

I think we should re-add a logging exporter configuration for now so that either can be used. We should also update the UPGRADING doc. In a future, telegraphed release we can remove the default logging export config.