WIP: keep indices on hot only 10h after rollover

refs: gitlab-com/gl-infra/production#3006 (comment 446271289)

We currently keep shards on hot nodes for 2d after rollover. This change reduces this time to 10h in an effort to reduce the number of shards in hot phase. Having a smaller number of shards should help speed up cluster recovery.

It should help with a more even distribution of shards (I'm actually not sure about this, marking this MR as WIP because of it, see the linked thread for more details).

This change, moves them to warm earlier. We currently use only 30% of disk space on warm nodes, so there should be enough space to hold these. Search latency might go up as a result, due to warm nodes generally having a lower spec.