Improve job dependency spec

What does this MR do and why?

Fixes spec/dot_gitlab_ci/job_dependency_spec.rb fails... (#473180 - closed) by

1. Switch from parallelized job names to non-parallelized job to do assertions
2. Ensure CI_PROJECT_NAME is also defined in addition to CI_PROJECT_PATH

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With the fixes in this MR, the spec now passes

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