Update GitLab Runner connectivity

What does this MR do?

Fix the wording of the connectivity between GitLab Runner and GitLab instance

GitLab is not talking to runners. It's runner that talks to GitLab. And the autoscaled VM that talks to GitLab (e.g. updating Git sources or downloading/uploading artifacts).

Unless one wants to configure and use the CI Web Terminal feature (which indeed requires communication from GitLab to runner) the communication is always made in one direction.

• !2418 (comment 414911231)

Related issues

!2418 (comment 414911231)

Author's checklist (required)

• Follow the Documentation Guidelines and Style Guide.
• If you have developer access or higher (for example, GitLab team members or Core Team members)
  • Apply the documentation label.
  • Assign the designated Technical Writer.

When applicable:

• Update the permissions table.
• Link docs to and from the higher-level index page, plus other related docs where helpful.
• Add GitLab's version history note(s).
• Add/update the feature flag section.
• If you're changing document headings, search docs/* for old headings and replace them with the new ones to avoid broken anchors.

Review checklist

All reviewers can help ensure accuracy, clarity, completeness, and adherence to the Documentation Guidelines and Style Guide.

1. Primary Reviewer

• Review by a code reviewer or other selected colleague to confirm accuracy, clarity, and completeness. This can be skipped for minor fixes without substantive content changes.

2. Technical Writer

• Technical writer review. If not requested for this MR, must be scheduled post-merge. To request for this MR, assign the writer listed for the applicable DevOps stage.
  • Ensure Technical Writing, documentation, and a docs:: scoped label are added.
  • Add docs-only when the only files changed are under docs/*.
  • Add twdoing when starting work on the MR.
  • Add twfinished if Technical Writing team work on the MR is complete but it remains open.

3. Maintainer

1. Review by assigned maintainer, who can always request/require the above reviews. Maintainer's review can occur before or after a technical writer review.
2. Ensure a release milestone is set.
3. If there has not been a technical writer review, create an issue for one using the Doc Review template.