Next iteration for measuring upgrade time betwen versions and plotting it

With gitlab-org/omnibus-gitlab!2298 (merged) , we completed the first iteration on measuring upgrade time between versions and plotting it. The constraints we decided were

1. Do minor-to-minor (10.5 => 10.6) and last-minor-to-major (10.8=>11.0) jumps only. Don't consider patch releases.
2. Use Google sheet to store the data and generate graph.

In future iterations, we need to tackle

1. Possibilities of measuring bigger version jumps, like 9.5.0 to 10.8.5.
2. Hooking it up with our Prometheus instance rather than using Google sheets.