Enable AWS life-cycle alongside SM

[regevran]

This comment describes a potential problem when S3 life-cycle is set and SSTables are not uploaded because they already exist on S3 (de-duplication).

The way to overcome it is to touch existing SSTables on S3, resetting their life cycle.
the touch is done as part of the de-duplication phase of the backup - making sure non-re-uploaded files reset their life-cycle.

The way to touch an S3 object is to either update its metadata or copy it to itself (or their might be other ways as well).
In either ways the timestamp is updated and the file will not be deleted as part of life-cycle management.

[mykaul]

It makes little sense to me to do it 'alongside' . We need a single owner of the life cycle. The challenge with doing it on the S3 side (which is great generally) is that unless you get the audit of the life cycle, objects just 'disappear' under your feet.

[regevran]

Quoting myself:

If SM misbehaves by "loosing" files, i.e. there are S3-objects that are not mapped to any backup - S3 itself will eventually remove them.