CI for triggering a delete of the ns

[xtineskim]

Describe the bug

I had to manually delete some ns of past PRs that were closed, for example #765, #727, even though they were merged/or manually closed. While this is not a super concerning, I would like to keep our resources running at a minimum to avoid incurring more charges.

To Reproduce

Not sure if it's reproducible, I didn't want to close any PRs. We can try opening fake PR and triggering the pr on event workflow?

Logs

n/a

Screenshots

n/a

Environment

n/a

Additional context

Whoever investigates this can reach out to me!

Exposure

n/a

[bourgeoisor]

@NimJay is this something you've seen recently by any chance?

[NimJay]

• Yes, this issue still exists.
• For instance, today, I see the workloads for pull-request 2201 still running inside the online-boutique-prs GKE cluster (of our Online Boutique CI project).

• The last time I did a manual clean up of this issue was around Aug 24.
• Today, there is only one PR that needs cleaning up (the PR mentioned above).
• The Aug 24 manual clean-up was for 10 pull-requests:
  • pr1636
  • pr1637
  • pr1640
  • pr1761
  • pr1767
  • pr1768
  • pr1939
  • pr1940
  • pr1943
  • pr1944
• Since we only got this issue once between Aug 24 and today (Oct 25), I assume we get this issue about once a month, so the p3 priority makes sense.
• Let's investigate when our team has more bandwidth. For now, a manual clean-up every few month is fine.