test for events after an opt out

[pnadolny13]

We should set up a test to alert us if events came in after an opt out event and before an opt back in event.

This would act as a second line of defense for catching bugs with the opt out flow (related to https://github.com/meltano/internal-data/issues/11#issuecomment-1227350788). If we get alerted we can take steps to delete those events from the warehouse to respect the opt out.