Saneitizer: Assign timestamps when creating events
When the fetches derived from saneitizer updates fail they sink to kafka, which then blows up because we never assigned any timestamps to the records that come from the SanitySource. Update the source to provide timestamps when sending events.
Bug: T358599 Change-Id: Ie14ddc62a4ff9a86578ecf3b58b07e2d65c000be