CloudWatch/Logs: Don't group dataframes for non time series queries (#37998)

* Don't split response when there is no time field

* Refactor grouping to separate function

* Add test

pkg/tsdb/cloudwatch/live_test.go

@@ -0,0 +1,31 @@
+package cloudwatch
+
+import (
+	"testing"
+
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGroupResponseFrame(t *testing.T) {
+	t.Run("Doesn't group results without time field", func(t *testing.T) {
+		frame := data.NewFrameOfFieldTypes("test", 0, data.FieldTypeString, data.FieldTypeInt32)
+		frame.AppendRow("val1", int32(10))
+		frame.AppendRow("val2", int32(20))
+		frame.AppendRow("val3", int32(30))
+
+		groupedFrame, err := groupResponseFrame(frame, []string{"something"})
+		require.NoError(t, err)
+		require.Equal(t, 3, groupedFrame[0].Rows())
+		require.Equal(t, []interface{}{"val1", "val2", "val3"}, asArray(groupedFrame[0].Fields[0]))
+		require.Equal(t, []interface{}{int32(10), int32(20), int32(30)}, asArray(groupedFrame[0].Fields[1]))
+	})
+}
+
+func asArray(field *data.Field) []interface{} {
+	var vals []interface{}
+	for i := 0; i < field.Len(); i++ {
+		vals = append(vals, field.At(i))
+	}
+	return vals
+}