Use tooltip component from gitlab-ui in jobs/components/job_container_item.vue

After https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22382 has been merged, jobs/components/job_container_item.vue should be refactored to use a tooltip component instead of a tooltip directive (see gitlab-ui#79 (closed) for the reasoning).

This requires refatoring the following tests:

• spec/javascripts/jobs/components/job_container_item_spec.js
• spec/features/projects/jobs/user_browses_job_spec.rb

(currently they are checking for title attribute which doesn't work with the tooltip component)