Use new location for gitlab-runner helm charts

What does this MR do?

Update references of gitlab-runner helm chart repos to new location. We are moving the project as per gitlab-org/distribution/team-tasks#422 (closed).

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry for user-facing changes, or community contribution. Check the link for other scenarios.
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content