This changes the logic for the alert validation in the extractor. Validation
is executed twice, once before attempting to save the alerts and once after
saving the dashboard while saving the alerts to the db. The first validation
will not require that the alert has a dashboard id which allows new dashboards
with alerts to be saved.
Fixes#11247
collapsed rows wrap the hidden rows within itself. This caused
the extractor to miss the panel and therefore delete the alert
accosiated with the graph.
closes#11222
If a panelId in the dashboard json is set to zero then the validation
silently fails. Instead of returning an error, it just ignores alerts and
saves the dashboard.
