ci: make it preemtible with pending upstream PRs

[blaggacao]

Example usage: frappe/erpnext#43473, #2252

@ruchamahabal could you merge for convenience?

[blaggacao]

@ruchamahabal Could you please merge this? It allows to validate if upstream PRs break downstream behaviour.

Otherwise, there is only the "screem test" * left and that's not ideal.

* go ahead and see if it hurts hrms downstream and then do damage control

_{Looks like we already have a damage control case here: #2259}