Switch to field_caps API

[spalger]

A part of #11011

With elastic/elasticsearch#23007 elasticsearch added a new API that provides a more integration-friendly look into the capabilities of fields in elasticsearch indexes. We should migrate to this API which is backed by mappings and will fix some unfortunate bugs introduced when we switched our field-capability-awareness to use the field stats API.

[s1monw]

w00t

[skearns64]

Nice!

@spalger - Are you planning to remove all uses of _field_stats within Kibana as part of this, or is this targeted just at the places where _field_caps would be used?

For example, I believe Kibana uses _field_stats to identify which indexes to query, when you have a wildcard index pattern. Will this remove that use as well?

[epixa]

@skearns64 Not as part of this specific ticket, but that will be the case after the linked meta issue for cross-cluster is complete. Though we won't be outright removing field_stats in the same version, we'll just deprecate that option for index patterns and remove it in a future major.

[s1monw]

@epixa @spalger @skearns64 I removed the shard limits in the upcoming 5.4 release so we should be able to just query instead of pre-select the indices.

[s1monw]

here is the issue elastic/elasticsearch#24012

[epixa]

@s1monw nice!

[ofirmgr]

in which version will @it be fixed?