pkg/services: Check errors (#19712)

* pkg/services: Check errors
* pkg/services: Don't treat context.Canceled|context.DeadlineExceeded as error

pkg/services/sqlstore/migrations/annotation_mig.go

@@ -155,6 +155,6 @@ func (m *AddMakeRegionSingleRowMigration) Exec(sess *xorm.Session, mg *Migrator)
 		}
 	}
 
-	sess.Exec("DELETE FROM annotation WHERE region_id > 0 AND id <> region_id")
-	return nil
+	_, err = sess.Exec("DELETE FROM annotation WHERE region_id > 0 AND id <> region_id")
+	return err
 }