monitoring: improved notification timings, resolved templates
Created by: bobheadxi
for https://github.com/sourcegraph/sourcegraph/issues/12026
- timings improvements
- group == alert, so reduce time to initial notification and increase re-notify time to 2d
- resolved vs firing
- after a closer look, I believe a lot of the spam in #alerts is actually alerts resolving - turns out the templates don't currently account for this