Uses CI_JOB_TOKEN over CI_REGISTRY_PASSWORD

What does this MR do?

This MR updates our .gitlab-ci.yml to use $CI_JOB_TOKEN over $CI_REGISTRY_PASSWORD

Why are we doing this?

It seems that authentication to our registry is currently broken and we are no longer able to login with our current credentials.

docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
WARNING! Using --password via the CLI is insecure. Use --password-stdin.
Error response from daemon: Get "https://registry.gitlab.com/v2/": unauthorized: HTTP Basic: Access denied

This MR changes how to login to the register by leveraging $CI_JOB_TOKEN which seems cleaner.

Container Registry (the $CI_REGISTRY_PASSWORD is $CI_JOB_TOKEN).

• Documentation authentication with CI_JOB_TOKEN.