[caffe2] add a Python test for SaveOp chunking
Summary:
Add a test in `load_save_test.py` that passes in a chunk_size parameter,
to ensure that we exercise the logic that passes the chunk size to the C++
serialization code.
Test Plan:
Ran the tests with the vlog level set to 3 and manually verified the log
messages showed that we were serializing in the expected chunks.
There are existing C++ tests that confirm chunking behavior works as expected
in the pure C++ code.
Reviewed By: mraway
Differential Revision: D26502578
fbshipit-source-id: cd0074f2358da81c68b0fed2c2a94818d83a957d
