SSE: DSNode to update result with names to make each value identifiable by labels (only Graphite and TestData) (#73642)

* SSE: DSNode to update result with names to make each value identifiable by labels (only Graphite and TestData) (#71246)

* introduce a function checkIfSeriesNeedToBeFixed to scan all value fields in the response and provide a function that updates Series so they can be uniquely identifiable. Only Graphite and TestData are checked.

* update `DSNode.Execute` to run this function and provide it to WideToMany
* update WideToMany to run the fix function if it is not nil

pkg/expr/service_test.go

@@ -20,7 +20,7 @@ import (
 func TestService(t *testing.T) {
 	dsDF := data.NewFrame("test",
 		data.NewField("time", nil, []time.Time{time.Unix(1, 0)}),
-		data.NewField("value", nil, []*float64{fp(2)}))
+		data.NewField("value", data.Labels{"test": "label"}, []*float64{fp(2)}))
 
 	me := &mockEndpoint{
 		Frames: []*data.Frame{dsDF},
@@ -65,7 +65,7 @@ func TestService(t *testing.T) {
 
 	bDF := data.NewFrame("",
 		data.NewField("Time", nil, []time.Time{time.Unix(1, 0)}),
-		data.NewField("B", nil, []*float64{fp(4)}))
+		data.NewField("B", data.Labels{"test": "label"}, []*float64{fp(4)}))
 	bDF.RefID = "B"
 
 	expect := &backend.QueryDataResponse{