saved searches should be excluded from search panels/alerts where possible

Created by: slimsag

A saved search encountering an error can inflate the search dashboards/alerts substantially, and is far less significant than a user encountering a search error. They should be excluded from the search panels where possible (e.g. for user alerts, successful/failed search counts, etc. but not for performance since that would not be possible) and separately monitored for failures in the query-runner service.

e.g. this is likely inflating this frontend dashboard panel on sourcegraph.com: