CloudWatch: Add labels for Metric Query type queries (#85766)

* CloudWatch: Fix metric query with group by not being labelled in alerts

* just use one key for the labels

* not needed

* unused function

* add tests

* pr comments

* fetch dimensions to build labels for MetricQuery type queries

* pr comments

* group cache related tests and use fresh cache for non-cache related tests

* don't cache empty values

pkg/tsdb/cloudwatch/time_series_query.go

@@ -96,11 +96,20 @@ func (e *cloudWatchExecutor) executeTimeSeriesQuery(ctx context.Context, req *ba
 					return err
 				}
 
-				if !features.IsEnabled(ctx, features.FlagCloudWatchNewLabelParsing) {
-					requestQueries, err = e.getDimensionValuesForWildcards(ctx, region, client, requestQueries, instance.tagValueCache, instance.Settings.GrafanaSettings.ListMetricsPageLimit)
-					if err != nil {
-						return err
+				newLabelParsingEnabled := features.IsEnabled(ctx, features.FlagCloudWatchNewLabelParsing)
+				requestQueries, err = e.getDimensionValuesForWildcards(ctx, region, client, requestQueries, instance.tagValueCache, instance.Settings.GrafanaSettings.ListMetricsPageLimit, func(q *models.CloudWatchQuery) bool {
+					if q.MetricQueryType == models.MetricQueryTypeSearch && (q.MatchExact || newLabelParsingEnabled) {
+						return true
 					}
+
+					if q.MetricQueryType == models.MetricQueryTypeQuery && q.MetricEditorMode == models.MetricEditorModeRaw {
+						return true
+					}
+
+					return false
+				})
+				if err != nil {
+					return err
 				}
 
 				res, err := e.parseResponse(ctx, startTime, endTime, mdo, requestQueries)