Enable auto-enable restricted access feature flags by default

What does this MR do and why?

Related to gitlab-org#21176 (closed), when a subscription does not allow overages, restricted access is auto-enabled on the group or instance. The changes in this MR prepares the SaaS and Self-managed feature flag rollout for auto-enabled restricted access feature.

• promotes auto_enable_restricted_access_on_self_managed from wip to beta
• promotes auto_enable_restricted_access_on_saas from wip to gitlab_com_derisk

References

• FF Rollout: auto_enable_restricted_access_on_saas (#596875)
• FF Rollout: auto_enable_restricted_access_on_se... (#596876)
• Sync contract_overages_allowed flag from Zuora ... (gitlab-org#21176 - closed)

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