APT_ORA_WRITE_FILES environment variable in DataStage

Set the APT_ORA_WRITE_FILES environment variable to prevent the invocation of the Oracle loader when write mode is selected on an Oracle Enterprise destination stage.

Instead, the sqlldr commands are written to a file, the name of which is specified by this environment variable. The file can be used after the job finishes to run the loaders sequentially to help track down export and pipe-safety issues that are related to the loader.