fix: remove unreachable oAuthToken auth type

[BoxBoxJason]

Description of your changes

This PR removes the dead OauthToken authentication method (it never existed in the first place)

Fixes #251

I have:

• Followed the git conventional commit message format.
• Made sure all changes are covered by proper tests, reaching a coverage of at least 80% when applicable.

How has this code been tested

I have:

• Made sure make lint passes to verify that the code style is correct.
• Made sure make test passes to verify that the code is working as intended.
• Made sure make e2e passes to verify that end-to-end tests pass against a real SonarQube instance.
• Added unit tests to cover the code changes.
• Added end-to-end tests if necessary.