SuperSonics: unlimited users

What does this MR do?

This MR addresses the following issue gitlab-org/gitlab#327729 by making sure the requirement is preserved that when usersInLicenseCount returns null the value should be set to Unlimited.

The feature is behind an Application Setting and it's not released nor documented. To test it locally, see the following steps.

1. Delete any previous license you might have

2. Make sure you have set the following vars

   • GITLAB_LICENSE_MODE is set to test
   • CUSTOMER_PORTAL_URL is set to https://customers.stg.gitlab.com

3. Use Rails console to run ApplicationSetting.current.update(cloud_license_enabled: true)

4. Navigate to admin/cloud_license

5. Use the following activation code: Lx6XhhLR1jSj2aacuZFRP8Mf

6. To test the failing scenario, simply block the network request to sync_seat_link

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because the feature is not active.
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team