Make test assertions more idiomatic (#2420)
* Codemod `unittest` assertions into native assertions
With https://github.com/akx/codemod-unittest-to-pytest-asserts
* Use plain asserts instead of `assertDict` and `assertList`
Done with
```
ast-grep run --pattern 'self.assertDictEqual($A, $B)' --rewrite 'assert $A == $B' -l python -i
ast-grep run --pattern 'self.assertListEqual($A, $B)' --rewrite 'assert $A == $B' -l python -i
``
* DRY some Deepspeed tests
