Update Ironbank to v15 (major)

This MR contains the following updates:

Package	Update	Change
ironbank/gitlab/gitlab-runner/gitlab-runner	major	v14.9.1 -> v15.0.0
registry1.dso.mil/ironbank/gitlab/gitlab-runner/gitlab-runner	major	v14.9.1 -> v15.0.0
registry1.dso.mil/ironbank/gitlab/gitlab-runner/gitlab-runner-helper	major	v14.9.1 -> v15.0.0

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This MR has been generated by Renovate Bot.