To optimize builds time on CI

[pawaskar-shreya]

This ticket can be viewed in 2 ways:

1. Is there a way we can avoid triggering the github builds for certain PRs
2. Is there a way we can optimize the time for builds. Currently the builds take 7-9 mins for most PRs and 9 to 12 mins on some PRs.

Build time throughout the project history:
6 mins --> 1-2 mins--> 6-7 mins (since dune pkg lock PR) --> 10 mins (for debug overlay, exception being - high time for Set up OCaml - 4 mins) --> 7-9 mins (for most recent PRs) --> 9-12 (for some PRs)

• Supposedly in one of the PRs, there was no time included for build checks and then 0 secs for run opam exec, post setup OCaml and post checkout tree. May be because it is a closed PR.

• Some of the PRs with consistent time being taken for builds

[pawaskar-shreya]

1. Is there a way we can avoid triggering the github builds for certain PRs

For 1, draft PR was explored to be opened in the below way:

1. Opened a PR
2. Converted it to draft but it still triggered the build

Other resources to explore along the lines:

1. https://stackoverflow.com/questions/68349031/only-run-actions-on-non-draft-pull-request
2. https://www.reddit.com/r/webdev/comments/1gbwhyo/draft_pull_request_always_only_me/