elastic: use millisecond-intervals (#54202)

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

@@ -106,7 +106,7 @@ export class ElasticQueryBuilder {
       esAgg.offset = settings.offset;
     }
 
-    const interval = settings.interval === 'auto' ? '$__interval' : settings.interval;
+    const interval = settings.interval === 'auto' ? '${__interval_ms}ms' : settings.interval;
 
     esAgg.fixed_interval = interval;
 

public/app/plugins/datasource/elasticsearch/specs/query_builder.test.ts

@@ -738,7 +738,7 @@ describe('ElasticQueryBuilder', () => {
             extended_bounds: { max: '$timeTo', min: '$timeFrom' },
             field: '@timestamp',
             format: 'epoch_millis',
-            fixed_interval: '$__interval',
+            fixed_interval: '${__interval_ms}ms',
             min_doc_count: 0,
           },
         },