Tighten permissions of the OONIDevopsPolicy AWS policy

[hellais]

The OONIDevopsPolicy could be a bit more narrowly scoped (

devops/tf/modules/adm_iam_roles/main.tf

Line 12 in c41f0d1

name = "OONIDevopsPolicy"

).

We should look into what's the minimal set of permissions necessary to allow it to perform the necessary terraform operations and limit its scope to only those.