Use Instant instead of Timestamp to ensure we always use UTC
Internally Gerrit events use milliseconds since the Epoch for event
timestamps which are in UTC by definition. Reflect this throughout the
events-log plugin by switching from `java.sql.Timestamp` to
`java.time.Instant` to ensure it always represents timestamps in UTC.
On Spanner this didn't work as intended since it assumes timezone PST
if the timezone isn't given explicitly.
Change-Id: I9f0e46fc3c33bf5502e9bfbfa755cccbe32b96e9
6 files changed
