TPS logs timestamps are stale?

[zerebubuth]

In 1e33d75, we started sending the TPS logs to CloudWatch. This is really useful, but would be more useful if the timestamps were recorded correctly.

CloudWatch log events have two timestamps; a timestamp for the event itself and an "ingestion" timestamp when CloudWatch first saw the event. Unfortunately, something we're doing wrong means that the event timestamp isn't being set correctly which, because the event timestamp is the one used in the CloudWatch GUI, makes it difficult to read through the logs.

This is probably something simple that I've overlooked, such as configuring CloudWatch to expect the timestamp in the same format as we're printing it out.