`test_typing.NewTypeTests` can be improved

[sobolevn]

After https://github.com/python/cpython/pull/103764/files#diff-04d29c98076c2d6bb75921ea9becb26a862544d39b71db87b6e354c759b9305dR6452 NewTypeTests has two unused methods:

• cleanup, it is even provided in its parent class: BaseTestCase
• teardown, because it does not need to clean things up, tests with -R 3:3 prove that

I will send a PR to clean things up.

Linked PRs

• gh-105431: Remove unused stuff from test_typing.NewTypeTests #105432
• [3.12] gh-105431: Remove unused stuff from test_typing.NewTypeTests (GH-105432) #105489