Updated links to pipelines topic

Why is this change being made?

I recently updated this topic in the main GitLab project: https://docs.gitlab.com/ee/ci/pipelines/

I renamed many of the titles to be more descriptive. This breaks links, so I fixed the ones that broke in this project.

Related to: gitlab-org/gitlab#205174 (closed)

How will this merge request impact page speed?

Should have no impact. It's replacing broken links with ones that work.

Does this MR meet the acceptance criteria?

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what