Reduce the number of service accounts autocreated for the cluster

[MKand]

Each cluster has a separate service account created by default. Might be an idea to create a single SA that is passed along to all the clusters

[stevemcghee]

i cautiously disagree. disabling a single global service account would take out multiple failure domains at once. that would be bad :)

[stevemcghee]

@muncus any opinion here?

[stevemcghee]

note: it looks like its coming from:

reliable-app-platforms/infra/terraform/gke/gke.tf

Line 15 in fb44920

create_service_account = true