CloudWatch: Refactor to extract DataQuery grouping by region out of request parsing (#57392)

* CloudWatch: Extract request parsing grouping by region from ParseQueries

* Rename ParseQueries to ParseMetricDataQueries

pkg/tsdb/cloudwatch/mocks/cloudwatch_metric_api.go

@@ -5,6 +5,7 @@ import (
 	"github.com/aws/aws-sdk-go/aws/request"
 	"github.com/aws/aws-sdk-go/service/cloudwatch"
 	"github.com/aws/aws-sdk-go/service/cloudwatch/cloudwatchiface"
+	"github.com/stretchr/testify/mock"
 )
 
 type FakeMetricsAPI struct {
@@ -56,3 +57,14 @@ func chunkSlice(slice []*cloudwatch.Metric, chunkSize int) [][]*cloudwatch.Metri
 
 	return chunks
 }
+
+type MetricsClient struct {
+	cloudwatchiface.CloudWatchAPI
+	mock.Mock
+}
+
+func (m *MetricsClient) GetMetricDataWithContext(ctx aws.Context, input *cloudwatch.GetMetricDataInput, opts ...request.Option) (*cloudwatch.GetMetricDataOutput, error) {
+	args := m.Called(ctx, input, opts)
+
+	return args.Get(0).(*cloudwatch.GetMetricDataOutput), args.Error(1)
+}