feat: add Reference Architecture monitoring of gitlab-sshd
Adds Reference Architecture support for gitlab-sshd.
Needed in support of https://gitlab.com/gitlab-com/gl-infra/gitlab-dedicated/team/-/issues/2136 for monitoring of gitlab-sshd.
This adds a gitlab-sshd SLI. The definition of the SLI matches GitLab.com's SSHd metric.
The change was tested in https://gitlab.com/gitlab-com/gl-infra/gitlab-dedicated/instrumentor/-/merge_requests/3255, and works as expected.
Edited by Andrew Newdigate