Decide on max instance lifetime for autoscaling groups

[manveru]

trafficstars

The maximum instance lifetime for autoscaling groups right now is set for each cluster separately and defaults to 0 (no TTL). While mantis- and vit-ops have it set to a week each. That was mostly for robustness testing but not ideal for production yet until we get persistence under control.

• [ ] Pick suitable lifetime and update dependent repos to use it.