The cloud API will be moved to `/api/composer/v1` in the future.
Mention this in the `servers` section of the openapi.yml (relative URLs
are allowed) too, even though our generator does not consider it.
Follow the worker API so we standardise on one library. This simplifies
the code quite a bit.
No functional change.
Signed-off-by: Tom Gundersen <teg@jklm.no>