Kibana 5.4.0 + ES 5.4.0 [_field_stats] endpoint is deprecated! Use [_field_caps] instead

[ZhukovAlexey]

Kibana version: 5.4.0

Elasticsearch version: 5.4.0

Server OS version: SUSE 12 SP1.

Original install method (e.g. download page, yum, from source, etc.): ES and KIbana are official Docker images.

Description of the problem including expected versus actual behavior:
There's a WARN message in ES deprecation.log

[WARN ][o.e.d.r.a.RestFieldStatsAction] [_field_stats] endpoint is deprecated! Use [_field_caps] instead or run a min/max aggregations on the desired fields.

Steps to reproduce:

1. Go to Management / Kibana / Index Pattern page or Discover page in Kibana.
2. Get [WARN ][o.e.d.r.a.RestFieldStatsAction] [_field_stats] endpoint is deprecated! Use [_field_caps] instead or run a min/max aggregations on the desired fields in ES deprecation.log

As it states here https://www.elastic.co/guide/en/elasticsearch/reference/current/search-field-stats.html

Deprecated in 5.4.0.
_field_stats is deprecated, use _field_caps instead or run an min/max aggregation on the desired fields

[jbudz]

Related #11114, #11014

[jbudz]

Closed by #12814