***Influxdb**: Add support for alerting on InfluxDB queries that use the non_negative_difference function [#15415](https://github.com/grafana/grafana/issues/15415), thx [@kiran3394](https://github.com/kiran3394)
***Alerting** Fix percent_diff calculation when points are nulls [#15443](https://github.com/grafana/grafana/issues/15443), thx [@max-neverov](https://github.com/max-neverov)
***Alerting**: Fix percent_diff calculation when points are nulls [#15443](https://github.com/grafana/grafana/issues/15443), thx [@max-neverov](https://github.com/max-neverov)
***Alerting**: Fixed handling of alert urls with true flags [#15454](https://github.com/grafana/grafana/issues/15454)
