Namespace api updates for customers that don't have a valid access_token
The change made in this MR removed the Admin token for GitLab api updates, switching to the customer's access token.
However TrialsController#create started failing because those customers do not have an access token.
There is also an issue with the Zuora Callback controller, in some cases it creates a brand new customer in some cases here: https://gitlab.com/gitlab-org/customers-gitlab-com/-/blob/staging/app/controllers/zuora_callbacks_controller.rb#L25 - this will need to be investigated as to how to get a valid access_token for them.
The MR was reverted for now to sort out the above two namespace API updates.
Next steps (if any)
Figure out if we can sync these customers at GitLab without the Admin token.