This change fixes an issue where a formerly warned/frozen user will be
warned again even though they have made payment for the invoice that got
them frozen in the first place. A payment status check is now made
right before a warn/freeze event to make sure the invoice hasn't been
paid already.
Issue: https://github.com/storj/storj/issues/5931
Change-Id: I3f6ac1e224f40107d58dc8f7bdbce58bbbea0196
