[PM] (NFC) Refactor the CGSCC pass manager tests to use lambda-based

passes.

This simplifies the test some and makes it more focused and clear what
is being tested. It will also make it much easier to extend with further
testing of different pass behaviors.

I've also replaced a pointless module pass with running the requires
pass directly as that is all that it was really doing.

llvm-svn: 280444