[Actionable Observability] Update an SLO

[kdelemme]

📝 Summary

Part of #137323
RFC

A user should be able to edit any existing SLO and change any fields from it.

As detailed in the RFC, when any properties but the indicator is updated on an SLO, the system will simply update the SLO saved object without introducing a new revision. In this case, the related transform does not need to be updated and the aggregated data is still valid.

When the indicator changes, the transform becomes invalid and the previously aggregated data too. In this case, we need to:

1. Bump the SLO revision
2. Update the SLO saved object
3. Stop and Remove the previously running transform: slo-{slo.id}-{slo.previous_revision}
4. Delete (asynchronously) the previously aggregated data using es deleteByQuery with (slo.id, slo.previous_revision)
5. Create and Start the new transform: slo-{slo.id}-{slo.revision}

✅ Acceptance Criteria

• Updating any fields but indicator, should only update the slo saved object
• Updating the indicator, should bump the slo revision, create a new transform and remove previous data

[elasticmachine]

Pinging @elastic/actionable-observability (Team: Actionable Observability)