final cleanup for PEM serialization

final cleanup originally started by #1564 
So, this test is using the `PKCS8` dir, while the other one that replaces it is using the PEM_Serialization dir. A comparison of the files in tehre shows that these are *not* the same. I think you probably want to update that test to check both for now? Notably the encryption mechanism is different -- PKCS8 uses PKCS8, and PEM_Serialization uses PEM encryption.