Stop sidekiq namespaced probes in gitlab-exporter

What does this MR do?

This MR stops the gitlab-exporter from probing sidekiq for namespaced keys. This is part of a series of releases in gitlab-com/gl-infra/scalability#2288 (closed).

In 16.4, we started polling both namespaces. In 16.6, we deprecate the use of namespace in Gitlab Rails and provided post-deployment migrations. Hence in 16.7, we are dropping the dual-polling support and removing metrics for namespaced keys in Sidekiq since a 16.6 -> 16.7 upgrade would see no metrics in the namespaced probes.

In 16.8, we are bumping the gitlab-exporter version to only poll non-namespaced Sidekiq keys.

Test plan

1. Deploy the chart from this branch using https://gitlab.com/gitlab-org/charts/gitlab/-/blob/master/doc/development/kind/index.md#nginx-ingress-nodeport-without-ssl
   • remember to set gitlab-exporter.enabled to true in examples/kind/values-base.yaml.
2. kubectl exec into the Toolbox Pod.
3. Run curl http://gitlab-gitlab-exporter:9168/metrics.
4. Confirm that no namespaced labels appear in the logs.

Related issues

Author checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, follow the instructions in the "Reviewer Roulette" section of the Danger Bot MR comment, as per the Distribution experimental MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added/updated
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened - gitlab-org/omnibus-gitlab!7237 (merged)
• Equivalent MR/issue for Gitlab Operator project opened (see Operator documentation on impact of Charts changes)
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.