alerting: return err when SetAlertState fails to save to sql (#18216)

fix duplicate alert states when the alert fails to save to the database.
fixes #18176

pkg/services/sqlstore/alert.go

@@ -298,7 +298,10 @@ func SetAlertState(cmd *m.SetAlertStateCommand) error {
 			alert.ExecutionError = cmd.Error
 		}
 
-		sess.ID(alert.Id).Update(&alert)
+		_, err := sess.ID(alert.Id).Update(&alert)
+		if err != nil {
+			return err
+		}
 
 		cmd.Result = alert
 		return nil