Renew expired SaaS error: Subscription is not upgradable
### Summary
Coming from MRs !2408 and !2674 to allow renewing expired subscriptions during a grace period. Possibly related to #2574.
[Customer](https://gitlab.zendesk.com/agent/tickets/204835) has an expired subscription which presents the `Renew` button because it's within grace period. Clicking that to enter the renew workflow (`/subscriptions/A-S00000000/renew`) results in
> Subscription is not upgradable
The order details can be found [in this note](https://gitlab.com/gitlab-com/support/internal-requests/-/issues/5689#note_549554909).
### Steps to reproduce
Try to renew the expired subscription
### Relevant logs and/or screenshots
[Sentry error](https://sentry.gitlab.net/gitlab/customersgitlabcom/issues/2551037/events/40208029/) states
> Errors::NotFoundError: Order not found
Which is thrown by [namespace_controller](https://gitlab.com/gitlab-org/customers-gitlab-com/-/blob/652029e95dd76d9d7597aa83d4d22db217f32841/app/controllers/gitlab/namespaces_controller.rb#L25) when [locating an order](https://gitlab.com/gitlab-org/customers-gitlab-com/-/blob/652029e95dd76d9d7597aa83d4d22db217f32841/app/controllers/gitlab/namespaces_controller.rb#L54-62).
Possibly, due to `.with_self_service_gitlab_plan` [scoping orders](https://gitlab.com/gitlab-org/customers-gitlab-com/-/blob/652029e95dd76d9d7597aa83d4d22db217f32841/app/models/order.rb#L34) to [Plan.self_service_gitlab_com_plans](https://gitlab.com/gitlab-org/customers-gitlab-com/-/blob/652029e95dd76d9d7597aa83d4d22db217f32841/app/models/plan.rb#L392-395):
```ruby
@@self_service_gitlab_com_plans ||= DEPRECATED_SAAS_GITLAB_PLANS +
[PREMIUM_SAAS_1_YEAR_PLAN, ULTIMATE_SAAS_1_YEAR_PLAN]
```
None of which appear to contain `FREE_PLAN`, which the expired order is set to via `product_rate_plan_id: "free-plan-id"`.
### Workarounds
- Sales assisted
- Purchase new subscription
### Reported examples
1. https://gitlab.zendesk.com/agent/tickets/204835
1. https://gitlab.zendesk.com/agent/tickets/206351
1. https://gitlab.zendesk.com/agent/tickets/212091
1. https://gitlab.zendesk.com/agent/tickets/211449
1. https://gitlab.zendesk.com/agent/tickets/212874
1. https://gitlab.zendesk.com/agent/tickets/251911
1. https://gitlab.zendesk.com/agent/tickets/253597
1. https://gitlab.zendesk.com/agent/tickets/254719
1. https://gitlab.zendesk.com/agent/tickets/257772
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