Added event and ref labels

[fheinecke]

Here's an example of the changes:

gha_workflow_run_time_seconds{event_type="schedule",ref="master",repo="teleport",workflow="dismiss"} 27
gha_step_run_time_seconds{event_type="schedule",job="Dismiss Stale Workflow Runs",ref="master",repo="teleport",step="Dismiss",workflow="dismiss"} 24
gha_step_run_count{conclusion="success",event_type="schedule",job="Dismiss Stale Workflow Runs",ref="master",repo="teleport",step="Dismiss",workflow="dismiss"} 1
gha_job_run_time_seconds{event_type="schedule",job="Dismiss Stale Workflow Runs",ref="master",repo="teleport",workflow="dismiss"} 27
gha_job_run_count{conclusion="success",event_type="schedule",job="Dismiss Stale Workflow Runs",ref="master",repo="teleport",workflow="dismiss"} 1

Another, merge group and branch/v14:

gha_step_run_count{conclusion="success",event_type="merge_group",job="Integration Tests (Non-root)",ref="branch/v14",repo="teleport",step="Checkout Teleport",workflow="integration-tests-non-root"} 1

[camscale]

I dont think this is an error - the value should either be empty or "unknown". Not every workflow run with a pull request event will be able to be tied back to a PR - the description of the pull_requests field in the "Get a workflow run" docs says

Pull requests that are open with a head_sha or head_branch that matches the workflow run. The returned pull requests do not necessarily indicate pull requests that triggered the run.

So if the pull request has closed at the time we query the the workflow runs, we may not get a PR. That's not an error, just bad timing, so I don't think the value should indicate an error.

[fheinecke]

Do you think "error-no-matching-open-pr" would be better, or maybe the head branch? I'm attempting to prefix all the "this is not what you would expect and should be filtered out in queries" values with the same prefix.

Pull requests that are open

I really hate this API...

[camscale]

LGTM. Let's give this a try and see what the metrics look like