Elasticsearch: Add support for Elasticsearch 8.0 (Beta) (#41729)

* use fixed_interval in date_histogram

* Add 8.0 to available versions in datasource settings

* Remove moving_avg from available metric aggregations

* Add ES8 devenv

* Update public/app/plugins/datasource/elasticsearch/components/QueryEditor/MetricAggregationsEditor/utils.ts

Co-authored-by: Piotr Jamróz <pm.jamroz@gmail.com>

* Add FE tests

* Add BE test

* fix FE test

* fix BE test

Co-authored-by: Piotr Jamróz <pm.jamroz@gmail.com>

pkg/tsdb/elasticsearch/client/models.go

@@ -239,6 +239,7 @@ type HistogramAgg struct {
 type DateHistogramAgg struct {
 	Field          string          `json:"field"`
 	Interval       string          `json:"interval,omitempty"`
+	FixedInterval  string          `json:"fixed_interval,omitempty"`
 	MinDocCount    int             `json:"min_doc_count"`
 	Missing        *string         `json:"missing,omitempty"`
 	ExtendedBounds *ExtendedBounds `json:"extended_bounds"`

pkg/tsdb/elasticsearch/client/search_request.go

@@ -342,6 +342,11 @@ func (b *aggBuilderImpl) DateHistogram(key, field string, fn func(a *DateHistogr
 		fn(innerAgg, builder)
 	}
 
+	if b.version.Major() >= 8 {
+		innerAgg.FixedInterval = innerAgg.Interval
+		innerAgg.Interval = ""
+	}
+
 	b.aggDefs = append(b.aggDefs, aggDef)
 
 	return b