Add link to log viewer for long logs

What does this MR do and why?

This change adds a link from the job details page to the log viewer when when the job log is too long to be displayed in the page.

Changelog: changed

Implements #455585 (closed)

Note: I had previously hidden this link while fixing this bug with !150802 (merged)

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

How to set up and validate locally

You need a job that's longer than the 499.95 KiB limit. You can use this .gitlab-ci.yml file:

long-job:
  script:
    - for i in {1..5000}; do echo "This is the very very very very very very very very very very very very very very very very very very very $ith long line"; done

Ensure you can select "view full log" in the header and view the full log.