Expressions: use datasource model from the query (#41376)

* refactor datasource loading

* refactor datasource loading

* pass uid

* use dscache in alerting to get DS

* remove expr/translate pacakge

* remove dup injection entry

* fix DS type on metrics endpoint, remove SQL DS lookup inside SSE

* update test and adapter

* comment fix

* Make eval run as admin when getting datasource info

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

* fmt and comment

* remove unncessary/redundant code

Co-authored-by: Kyle Brandt <kyle@grafana.com>
Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>
Co-authored-by: Santiago <santiagohernandez.1997@gmail.com>

pkg/services/query/query.go

@@ -87,10 +87,7 @@ func (s *Service) handleExpressions(ctx context.Context, user *models.SignedInUs
 			RefID:         pq.query.RefID,
 			MaxDataPoints: pq.query.MaxDataPoints,
 			QueryType:     pq.query.QueryType,
-			Datasource: expr.DataSourceRef{
-				Type: pq.datasource.Type,
-				UID:  pq.datasource.Uid,
-			},
+			DataSource:    pq.datasource,
 			TimeRange: expr.TimeRange{
 				From: pq.query.TimeRange.From,
 				To:   pq.query.TimeRange.To,