Disabling Geo nodes does not work as expected

I've seen a few suspect areas where GeoNode#enabled? appears not to be respected. We should audit all Geo-gated functionality and ensure that it functions correctly if a Geo node is present, but disabled.

Alternatively, we could remove this functionality altogether. It doesn't seem useful to me.

If a secondary is present, but disabled, should we queue or discard geo log cursor events intended for it? Discarding seems dangerous as it may allow the secondary to get out of sync in non-recoverable ways when re-enabled.

It might be better to consider (and reimplement) this as a "pause" button if we go the pause route?

/cc @jramsay