format thrift/lib/cpp2/test/ChannelTest.cpp
format thrift/lib/cpp2/test/ChannelTest.cpp

Summary:
touched thrift/lib/cpp2/test/ChannelTest.cpp and ran `arc lint`
as titled

Reviewed By: andriigrynenko

Differential Revision: D19591964

fbshipit-source-id: e6bfbe8e8a2fc9935894ec405c614e968520cf6f

facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift