ILM optimized migrate for searchable snapshot action #68635
Description
Today, the migrate action will execute before the searchable snapshot action.
If tiers are separated on different sets of nodes, this means that the shards are
first transferred to the new tier (cold for instance) and then afterwards mounted
as searchable snapshots on that same tier.
It seems we could be more optimal here by not doing the migrate step on the
existing index and instead assign the mounted index directly to the target tier.