Alerting: Fix alerting evaluation to use proper permissions (#55127)

* access control to log user name if it does not have permissions
* update ngalert Evaluator to accept user instead of creating a pseudo one
* update alerting eval (rule\query testing) API to provide the real user to the Evaluator
* update scheduler to create a pseudo user with proper permissions

pkg/services/ngalert/api/api_testing.go

@@ -53,7 +53,7 @@ func (srv TestingApiSrv) RouteTestGrafanaRuleConfig(c *models.ReqContext, body a
 		now = timeNow()
 	}
 
-	evalResults := srv.evaluator.ConditionEval(c.Req.Context(), evalCond, now)
+	evalResults := srv.evaluator.ConditionEval(c.Req.Context(), c.SignedInUser, evalCond, now)
 
 	frame := evalResults.AsDataFrame()
 	return response.JSONStreaming(http.StatusOK, util.DynMap{
@@ -115,7 +115,7 @@ func (srv TestingApiSrv) RouteEvalQueries(c *models.ReqContext, cmd apimodels.Ev
 		return ErrResp(http.StatusBadRequest, err, "invalid queries or expressions")
 	}
 
-	evalResults, err := srv.evaluator.QueriesAndExpressionsEval(c.Req.Context(), c.SignedInUser.OrgID, cmd.Data, now)
+	evalResults, err := srv.evaluator.QueriesAndExpressionsEval(c.Req.Context(), c.SignedInUser, cmd.Data, now)
 	if err != nil {
 		return ErrResp(http.StatusBadRequest, err, "Failed to evaluate queries and expressions")
 	}