pytest complains PytestCollectionWarning when a class name looks
like a test case class ("TestFoo").
We can disable the warning by adding '__test__ = False' but
it looks easier to drop "Test" prefix from such classes.
This commit drops "Test" prefix if we can simpy drop it from
class names. If a class name will be too generic after dropping
"Test" prefix, I renamed such classes from "TestFoo" to "FooForTesting"
as a workaround.
Change-Id: I617ab8462a9dc173e34f4aae899e0b0def6ecdc1
c34cc5c06f