integration: rename get_thrift_client to get_thrift_client_legacy
integration: rename get_thrift_client to get_thrift_client_legacy

Summary:
This makes it consistent with the naming in the CLI, and will allow introducing
a get_thrift_client for streaming APIs.

Reviewed By: genevievehelsel

Differential Revision: D35767106

fbshipit-source-id: deb45090875b0366111e16e27abba22858b8f370

facebook/watchman,facebook/watchman,facebook/watchman,facebook/watchman,facebook/watchman,facebook/watchman,facebook/watchman,facebook/watchman,facebook/watchman