Fix the tests in rcsb/db/tests*

[brindakv]

Specifically, tests-validate/testSchemaDataPrepValidate.py throws errors.

Traceback (most recent call last):
  File "~/py-rcsb_db/rcsb/db/define/SchemaDefAccess.py", line 196, in getPrivateDocumentAttributes
    return [d for d in self.__documentDefDict["COLLECTION_DOCUMENT_PRIVATE_KEYS"][collectionName]]
                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
KeyError: 'pdbx_core_entity'

Traceback (most recent call last):
  File "~/py-rcsb_db/rcsb/db/define/SchemaDefAccess.py", line 196, in getPrivateDocumentAttributes
    return [d for d in self.__documentDefDict["COLLECTION_DOCUMENT_PRIVATE_KEYS"][collectionName]]
                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
KeyError: 'pdbx_core_entity_instance'