Backend: Harden CI limit for public projects

Problem to solve

In #243722 (closed) we give a cost factor 0.008 to all public projects. Before that, public projects in namespaces created before July 2021 had unlimited CI minutes. With #243722 (closed) we have put an end to unlimited CI minutes.

As we do #346400 (closed) we then need to raise the baseline cost factor for public projects that are not public forks to 1, so that 0.008 cost factor applies only to public forks.

Proposal

• Raise default cost factor for public projects from 0.008 to 1.0.
• Ensure that the rules for public forks get cost factor 0.008 and rules for OSS projects get cost factor .5 prevail over this cost factor

Cost Factor proposal

• Now - Cost factor .008
• Sept 1 (15.4) - Set Cost Factor to .04 - issue for SRE team - gitlab-com/gl-infra/production#7628 (closed)
• Oct 1 (15.5) - Set Cost Factor to 1 - issue for SRE team - gitlab-com/gl-infra/production#7640 (closed)
  • As soon as the cost factor is set to 1 our algorithm that selects the lowest cost factor could select 0.5 for public Open Source plan projects. We need to document that.

Acceptance criteria / testing

• A user on Free (or any) plan is charged with a 0.008 cost factor if they run a pipeline on a public fork of a public project.
• A user on any plan is charged with a 1 cost factor if they run a pipeline on a project that is not a public fork of a public project.

Technical Work

We opened 2 change management issues for the SRE team here:

• gitlab-com/gl-infra/production#7628 (closed)
• gitlab-com/gl-infra/production#7640 (closed)

Once those issues are closed grouppipeline execution verify this via cost factor logging and close this one out.