E2E: Move github import specs to orchestrated job

What does this MR do and why?

Unquarantine github spec and move it to orchestrated job with other import specs.

A global mock of github still needs to be created in order to not run in to potential api rate limit errors in the future, but the task has proved itself fairly non trivial. Meanwhile we should be able to run github spec as orchestrated scenario only to have some coverage.

Closes Failure in api/1_manage/import/import_github_re... (#382457 - closed)
Closes Failure in browser_ui/1_manage/project/import_g... (#382001 - closed)

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