feat: Set a default value to the `event_timestamp` field

Describe the bug After going through the quickstart. The Kibana records don’t contain time information, besides, last_updated.

To Reproduce Steps to reproduce the behavior:

1. Initialize your Argilla with Kibana
2. Upload the quickstart.
3. Create a Kibana index pattern based on event_timestamp
4. No record show due to empty field.

Expected behavior I would expect to have this set to the same date as event_timestamp, until someone has annotated the data and therefore updated.

Screenshots If applicable, add screenshots to help explain your problem.

Environment (please complete the following information):

• OS [e.g. iOS]: MacOS
• Browser [e.g. chrome, safari]: Firefox
• Argilla Version [e.g. 1.0.0]: 1.0.1
• ElasticSearch Version [e.g. 7.10.2]: 7.10.2
• Docker Image (optional) [e.g. argilla:v1.0.0]: argilla:v1.0.1

Additional context Maybe we can align this with other kibana issues #1803.

[frascuchon]

So, I think we can move as a feature request and place it in the roadmap. Adding this default behavior could conflict with the way Argilla indexes the data, and we need to think about how to handle it.

[davidberenstein1957]

event_timestamp -> creation_time deprecate event_timestamp and creation_time should always be included