Four Keys for Dora.dev

[davidstanke]

Hey team -- I've installed a Four Keys dashboard onto dora.dev: https://fourkeys-grafana-dashboard-gr5oklvxhq-ue.a.run.app/d/yVtwoQ4nk/four-keys?orgId=1

...there's of course not much in it yet. Policy change: in order to support Four Keys, I've changed the allowed merge strategy for Dora.dev... we used to use squash and merge, but that strategy erases the commits that had been part of the PR and creates a new one at the time of merge. This means the "commit to prod" time would measure only the duration of the CI process. We want to reflect the human parts as well (although it's an open question whether we want to measure from the start of coding, or from the start of peer review). So, the allowed merge strategy is now merge commit, which preserves (all of) the commits leading up to the merge, allowing us to compute on those.

[davidstanke]

FYI @jessegduke @sapientcoffee