Alerting: better Alert previews (blocked: structured API response)

[gillesdemey]

The alert previews are currently very information dense and do not allow for fast feedback, we should take another look at the design of the previews and make sure they properly inform the user about the output of the rule definition.

[dbluxo]

When creating alerts based on Prometheus, I discovered "preview alerts". Here I would be very interested to know how often and when this alert would have fired based on the selected datasource (Prometheus data) to get a feel for if this is what I expect based on the historical data. Currently I get this overview, which is very confusing or does not help at all:

[grafanabot]

This issue was removed from the 8.5.0-beta1 milestone because 8.5.0-beta1 is currently being released.

[gillesdemey]

Setting this to "blocked" until we can get some work done on the API to return a more structured response that enabled us to receive the labels and values that are computed.