These ENV vars are:
- CLOUDSTACK_ZONE
- CLOUDSTACK_DOMAIN
- CLOUDSTACK_ACCOUNT
- CLOUDSTACK_PROJECT
help to DRY on every task, args still have precedence.
Trying to preserve the meaning of the examples. Not all occurrences in
`docsite/rst/playbooks_lookups.rst` have been changed for instance to
allow the unchanged examples to be used for testing.
Related to: #17479