Change CI errors to split on a newline

What does this MR do and why?

In the current release of GitLab, .gitlab-ci.yml errors are split on a comma (",") when viewing the status of a pipeline. This can cause problems in the front-end, as some errors contain commas and split the sentence into a new bullet point.

The strings are contained within lib/gitlab/ci/pipeline/seed/build.rb

This MR changes the comma to a newline ("\n")in the show.html.haml file, which now splits the errors correctly, as shown in the examples below.

Screenshots or screen recordings

Example 1 (Maximum Needs)

Before	After

|

"#{name}: one job can only need #{max_needs_allowed} others, but you have listed #{@needs_attributes.size}. See needs keyword documentation for more details"

Example 2 (Needs is Missing)

Before	After

|

"'#{name}' job needs '#{need[:name]}' job, but '#{need[:name]}' is not in any previous stage" 

How to set up and validate locally

If running this branch, on your local GitLab instance create an empty project. Create a .gitlab-ci.yml file, and use the below contents to generate an error:

stages:
  - init
  
pre structure:
    stage: .pre
    script:
      - echo "hello"
    only:
      - tags 


download base data files:
  stage: init
  script:
    - echo "hello"
  needs:
    - pre structure
  rules:
    - if: '$DATES_TO_PROCESS != "0"'

Navigate to CI > Pipelines, and the pipeline will have failed. Note that the error message is displayed in one-line without being split on the comma.

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.