SAR-255 Used the SKA_K8S_TOOLS_DEPLOY_IMAGE group-level variable for the ci image

.gitlab-ci.yml

 # GitLab CI in conjunction with GitLab Runner can use Docker Engine to test and build any application.
 # Docker, when used with GitLab CI, runs each job in a separate and isolated container using the predefined image that is set up in .gitlab-ci.yml.
 # In this case we use the latest python docker image to build and test this project.
-image: nexus.engageska-portugal.pt/ska-docker/ska-python-buildenv:latest
+image: $SKA_K8S_TOOLS_DEPLOY_IMAGE
 
 # cache is used to specify a list of files and directories which should be cached between jobs. You can only use paths that are within the project workspace.
 # If cache is defined outside the scope of jobs, it means it is set globally and all jobs will use that definition