Simplify internal anchors error presentation

What does this MR do and why?

I've been working on splitting some pages, and I've been using the internal anchor test a lot to fix the errors. My eyes hurt each time I look at the job log.

I tried to simplify the error by removing the anchor since it's anyway reported again in the destination output, which I changed to read anchor link. I believe the output is a bit clearer now.

A continuation of #1723.

Screenshots, screen recordings, or links to review app

Before

Issues found!
  (global):
    [ ERROR ] internal_anchors - Broken anchor detected: `#message-error-canceling-statement-due-to-conflict-with-recovery`
      - source file `/Users/axil/devel/gitlab/gdk/gitlab-docs/public/ee/administration/geo/index.html`
      - destination `replication/troubleshooting/index.html#message-error-canceling-statement-due-to-conflict-with-recovery`
    [ ERROR ] internal_anchors - Broken anchor detected: `#message-log--invalid-cidr-mask-in-address`
      - source file `/Users/axil/devel/gitlab/gdk/gitlab-docs/public/ee/administration/postgresql/pgbouncer.html`
      - destination `../geo/replication/troubleshooting/index.html#message-log--invalid-cidr-mask-in-address`
    [ ERROR ] internal_anchors - Broken anchor detected: `#message-log--invalid-ip-mask-md5-name-or-service-not-known`
      - source file `/Users/axil/devel/gitlab/gdk/gitlab-docs/public/ee/administration/postgresql/pgbouncer.html`
      - destination `../geo/replication/troubleshooting/index.html#message-log--invalid-ip-mask-md5-name-or-service-not-known`
    [ ERROR ] internal_anchors - Broken anchor detected: `#resync-and-reverify-individual-components`
      - source file `/Users/axil/devel/gitlab/gdk/gitlab-docs/public/ee/administration/troubleshooting/gitlab_rails_cheat_sheet.html`
      - destination `../geo/replication/troubleshooting/index.html#resync-and-reverify-individual-components`
    [ ERROR ] internal_anchors - Broken anchor detected: `#fixing-postgresql-database-replication-errors`
      - source file `/Users/axil/devel/gitlab/gdk/gitlab-docs/public/ee/administration/troubleshooting/postgresql.html`
      - destination `../geo/replication/troubleshooting/index.html#fixing-postgresql-database-replication-errors`

After

Issues found!
  (global):
    [ ERROR ] internal_anchors - Broken anchor detected:
      - source file `/Users/axil/devel/gitlab/gdk/gitlab-docs/public/ee/administration/geo/index.html`
      - anchor link `replication/troubleshooting/index.html#message-error-canceling-statement-due-to-conflict-with-recovery`
    [ ERROR ] internal_anchors - Broken anchor detected:
      - source file `/Users/axil/devel/gitlab/gdk/gitlab-docs/public/ee/administration/postgresql/pgbouncer.html`
      - anchor link `../geo/replication/troubleshooting/index.html#message-log--invalid-cidr-mask-in-address`
    [ ERROR ] internal_anchors - Broken anchor detected:
      - source file `/Users/axil/devel/gitlab/gdk/gitlab-docs/public/ee/administration/postgresql/pgbouncer.html`
      - anchor link `../geo/replication/troubleshooting/index.html#message-log--invalid-ip-mask-md5-name-or-service-not-known`
    [ ERROR ] internal_anchors - Broken anchor detected:
      - source file `/Users/axil/devel/gitlab/gdk/gitlab-docs/public/ee/administration/troubleshooting/gitlab_rails_cheat_sheet.html`
      - anchor link `../geo/replication/troubleshooting/index.html#resync-and-reverify-individual-components`
    [ ERROR ] internal_anchors - Broken anchor detected:
      - source file `/Users/axil/devel/gitlab/gdk/gitlab-docs/public/ee/administration/troubleshooting/postgresql.html`
      - anchor link `../geo/replication/troubleshooting/index.html#fixing-postgresql-database-replication-errors`

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Configure a local GitLab Docs environment: https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/doc/setup.md.
2. Check out this branch.
3. Edit a doc page that contains an anchor link and remove a character from that anchor link.
4. Run the check and see it fail:

   bundle exec nanoc check internal_anchors

Merge request acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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