Tracking.rb sends wrong creation timestamp to snowplow - it should send in milliseconds
Solution: Snowplow expects timestamps in milliseconds.
## Background
`dvce_created_tstamp` in snowplow is wrong possibly due to a wrong timestamp being sent from Ruby.
So we have 3 timestamps created sent and collector tstamp sent and collector are correctly set up not created
```
select derived_tstamp, dvce_sent_tstamp, dvce_created_tstamp, collector_tstamp, *
from snowplow.gitlab_events
where
v_tracker LIKE 'rb-%'
limit 200
```
- https://gitlab.com/gitlab-data/analytics/issues/3097#note_253487440
- https://gitlab.com/gitlab-org/gitlab/blob/master/lib%2Fgitlab%2Ftracking.rb#L32
- https://gitlab.com/gitlab-org/growth/engineering/issues/2598
issue