chore(ci-cn): starting 2023/06/22, CN5G  images do not support anymore env-variable-based deployment configuration

* A common YAML file shall be mounted
* Currently SPGWU-TINY is still using the old configuration scheme
  - But a new UPF is soon to be released

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>