Use GitLab CI variables when available in arkindex workers publish

GitLab runners can clone repositories in weird ways that may make the usual git commands not work.

The arkindex workers publish command should prioritize the predefined CI variables over running git commands whenever available:

--repository-url "$CI_PROJECT_URL"
--revision-hash "$CI_COMMIT_SHA"
--revision-message "$CI_COMMIT_MESSAGE"
--revision-author "$CI_COMMIT_AUTHOR" # This is "Name <email>" format, please remove the email
--revision-branch "$CI_COMMIT_BRANCH"
--revision-tag "$CI_COMMIT_TAG"