SSE: Refactor to simplify Series type (#35063) (#35123)

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>
(cherry picked from commit 4093fae99a)

Co-authored-by: Kyle Brandt <kyle@grafana.com>

pkg/expr/service_test.go

@@ -22,7 +22,7 @@ import (
 // nolint:staticcheck // plugins.DataPlugin deprecated
 func TestService(t *testing.T) {
 	dsDF := data.NewFrame("test",
-		data.NewField("time", nil, []*time.Time{utp(1)}),
+		data.NewField("time", nil, []time.Time{time.Unix(1, 0)}),
 		data.NewField("value", nil, []*float64{fp(2)}))
 
 	dataSvc := tsdb.NewService()
@@ -61,7 +61,7 @@ func TestService(t *testing.T) {
 	require.NoError(t, err)
 
 	bDF := data.NewFrame("",
-		data.NewField("Time", nil, []*time.Time{utp(1)}),
+		data.NewField("Time", nil, []time.Time{time.Unix(1, 0)}),
 		data.NewField("B", nil, []*float64{fp(4)}))
 	bDF.RefID = "B"
 
@@ -90,11 +90,6 @@ func TestService(t *testing.T) {
 	}
 }
 
-func utp(sec int64) *time.Time {
-	t := time.Unix(sec, 0)
-	return &t
-}
-
 func fp(f float64) *float64 {
 	return &f
 }