Add e2e test to push using a private token

What does this MR do?

Adds an end-to-end test that uses a personal access token to push over HTTP(S).

What are the relevant issue numbers?

gitlab-com/gl-infra/production#536 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.