Fix some broken tests for the OAuth API endpoint.
Fix some broken tests for the OAuth API endpoint.

There were two tests for the OAuth endpoint which were broken because
they were checking the `PUT` result, but the tests were for the `DELETE`
operation. This wasn't caught because the test method names were typoed
and therefore weren't running (they were `def def_test...` instead of
`def test...`).

Testing Done:
Fixed the test method names and saw two new failures. Fixed the test
bodies and saw the tests pass.

Reviewed at https://reviews.reviewboard.org/r/12117/

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