1. BackupCursor Unit Tests use BackupBlock interface improperly (functional)

Some unit tests in the enterprise repo improperly pass in a filename stem instead of a filepath to the BackupBlock() constructor. Much of this code is brittle. Some examples:

• TestTypicalCursorLifetime (backup_cursor_service_test.cpp)
• TestFilenameCheck (document_source_backup_cursor_test.cpp)

2. _forTest & _ForTest naming is inconsistent (style)

standardize on _forTest which is more prevalent

src/fcbis/file_copy_based_initial_syncer.h

src/fcbis/file_copy_based_initial_syncer_test.cpp

• getBackupCursorFiles_ForTest
• getExtendedBackupCursorFiles_ForTest

• setOldStorageFilesToBeDeleted_ForTest
  • corollary: getOldStorageFilesToBeDeleted_forTest