Datum token rotation is not happening right now

- With Datum as the metric/log service manager, central mints out 2 tokens - datum metric token, and datum log token
- The expiry of these 2 JWTs are 7 days.
- [Line](https://github.com/frappe/central/blob/79747dae48883f0676f30a0ffb08c75f89e851c6/central/sso.py#L18) says that pilot will refetch the tokens when its near expiry.
- But currently there are no implementation of that in pilot side.
- We need a way for the token consumers to refetch/renew the tokens or make the tokens long lived.

Start with central/sso.py at the referenced line and trace how Datum metric and log JWTs are consumed by pilot. Decide whether consumers should refetch tokens near the seven-day expiry or use long-lived tokens; done means both tokens are renewed or remain valid without manual intervention.

Written by the indexing model from the issue text.