Refs. #5519

Refs. #5240

That many actions less to do when creating a new task.

We usually do both staging then production environment when no issues arise in staging.

Refs. #4795

This can be iterated upon to improve.

Refs. #4740

Infra repositories and docker images are now under /swh/infra; Private
repositories are under /infra-private.

Ref. #4714

Related to T4066