[Examples] add venue label filepath; delete redundant code

[chenjw505]

Description

the code of examples/pytorch/metapath2vec/test.py has 2 bugs

Changes

Fix1, add the venue label filepath, it's file_1 that miss in code

Fix2, there are some redundant code for split the train and test data；
annotate the print in loop of authors which is much more print information；

[BarclayII]

Thank you so much!