Elasticsearch: Name fields after template variables values instead of their name (#36035)

This reverts commit 185bf8f9a2.

public/app/plugins/datasource/elasticsearch/datasource.ts

@@ -35,7 +35,6 @@ import {
 import { bucketAggregationConfig } from './components/QueryEditor/BucketAggregationsEditor/utils';
 import {
   BucketAggregation,
-  BucketAggregationWithField,
   isBucketAggregationWithField,
 } from './components/QueryEditor/BucketAggregationsEditor/aggregations';
 import { generate, Observable, of, throwError } from 'rxjs';
@@ -391,23 +390,7 @@ export class ElasticDatasource extends DataSourceApi<ElasticsearchQuery, Elastic
       this.templateSrv.replace(JSON.stringify(expandedQueries), scopedVars)
     );
 
-    // FIXME: with 8.0 we introduced an undocumented breaking change on how we name frames fields.
-    // Although the introduced behavior is correct, it wasn't documented.
-    // The following lines will restore the previous behaviour for 8.0, to be removed with a proper
-    // changelog in 8.1 by returning `finalQueries` without any further modification
-    return finalQueries.map((q, queryIndex) => ({
-      ...q,
-      bucketAggs: q.bucketAggs?.map((bucketAgg, aggIndex) => {
-        if (isBucketAggregationWithField(bucketAgg)) {
-          return {
-            ...bucketAgg,
-            field: (queries[queryIndex].bucketAggs?.[aggIndex] as BucketAggregationWithField).field,
-          };
-        }
-
-        return bucketAgg;
-      }),
-    }));
+    return finalQueries;
   }
 
   testDatasource() {