Expressions: Fixes the issue showing expressions editor (#62510)

* Use suggested value for uid

* update the snapshot

* use __expr__

* replace all -100 with __expr__

* update snapshot

* more changes

* revert redundant change

* Use expr.DatasourceUID where it's possible

* generate files

pkg/services/ngalert/api/authorization_test.go

@@ -401,7 +401,7 @@ func TestCheckDatasourcePermissionsForRule(t *testing.T) {
 	expressionByType := models.GenerateAlertQuery()
 	expressionByType.QueryType = expr.DatasourceType
 	expressionByUID := models.GenerateAlertQuery()
-	expressionByUID.DatasourceUID = expr.OldDatasourceUID
+	expressionByUID.DatasourceUID = expr.DatasourceUID
 
 	var data []models.AlertQuery
 	var scopes []string