Integration test scenario for https://customers.stg.gitlab.com

Create integration test scenario for testing customers.stg.gitlab.com

Dependent on: https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/6085


https://customers.gitlab.com portal is an important part of GitLab that serves as a billing engine for gitlab.com as well as self hosted instances and is used by customers and the GitLab support engineering team. It allows GitLab users to signup for paid plans, manage their subscriptions, payment methods and view payment history. GiLab support engineers can use this portal to view and update customer information and EULA records. User's subscription information from customers.gitlab.com portal is used on Gitlab.com to enable features available for the subscribed plan.

We have new features and improvements planned for the customers.gitlab.com portal as describled in the Customer portal vision epic

With this epic, we setup E2E testing framework for customers.gitlab.com and automate some basic test cases.

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Issue for reviving https://customers.stg.gitlab.com: https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/6085

Edited by Ramya Authappan