Create deployment blockers dashboard

This MR creates a Deployment Blockers dashboard for this issue. This is to capture the trend of recurring root causes of the deployment blockers, so we can display and observe the frequency changes as we modify our processes.

You can check this test dashboard where I manually imported a JSON file generated from my local: Deployment Blockers Test Dashboard. To recreate the dashboard (to see the actual view with the data), generate the JSON file by running: ./dashboards/generate-dashboards.sh and import the JSON file to the Grafana Playground folder.