Add pipeline durations panels to RM toils and deploy-metric dashboards

Addresses issue: gitlab-com/gl-infra/delivery#2929 (closed) to visualize the durations of auto-deploy pipelines and their downstream pipelines.

The last bar gauge panel of RM toil dashboard in the snapshot shows the durations of the deployment pipelines for all the versions in the time range. (There's a caveat that it sometimes shows a lot more than the deploy versions that deployed in the time range, but that's the behaviour of the metric, not the visualization: thanos query)

Those bar gauges are click-through-able, and it will take the user to the deployment-metrics dashboard, where it will display version-specific details. That dashboard will now have per-environment-stage bar gauge panel to indicate duration for each downstream pipeline, alongside a total deploy time for that version.

Feel free to suggest some thresholds. I put in some values (in seconds), but it might be too strict/relaxed.

(24 hours expiry) RM Toil dashboard: https://dashboards.gitlab.net/dashboard/snapshot/M0Pk4UbtrR5DIfkJyrLDCdGXMdPS1tKL?orgId=1 Deployment-metrics: https://dashboards.gitlab.net/dashboard/snapshot/rGyrlPCS6Tq2bJyQwgLOhhr2sYA43IAI?orgId=1&from=now-2d&to=now

$ ./test-dashboard.sh delivery/release_management_toil.jsonnet
Installed https://dashboards.gitlab.net/dashboard/snapshot/IXnYI7LH3jDVONF3ZTUKXGX4yAxH8RoP - delivery: Release Management Toil

./test-dashboard.sh delivery/deployment_metrics.jsonnet
Installed https://dashboards.gitlab.net/dashboard/snapshot/y49mL3zfb7xE981zi1dMhnI46hf0yh0K - delivery: deployment-metrics