Use job name for primary identifier on ci header

What does this MR do and why?

This MR changes the primary identifier for a job from the ID to the job name on the job log show view. We have to touch the component app/assets/javascripts/vue_shared/components/header_ci_component.vue which is shared with the pipelines show view as well.

I have made the itemId prop not required and based on if it's passed or not we render different strings. For the job page we will render Job job_name and for the pipeline page we will render Pipeline #123.

Related to: #336986 (closed)

Screenshots or screen recordings

before	after

These are strongly recommended to assist reviewers and reduce the time to merge your change.

How to set up and validate locally

You will need a local runner and able to run a pipeline/job. Or use a test project already created by GDK that has pipelines and jobs.

Visit a pipeline and ensure the ID is still displayed as identifier in the CI header.

Visit a job log and ensure the job name is used as the identifier in the CI header.

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• Deployment checklist confirmed

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2. I have informed the Infrastructure department of a default setting or new setting change per definition of done, or decided that this is not needed.

Related to #336986 (closed)