Shift SocketAddressTest from socketpair to netops::socketpair
Shift SocketAddressTest from socketpair to netops::socketpair

Summary: I missed a use of file descriptors in the last diff to clean up this test.

Reviewed By: yfeldblum

Differential Revision: D12990054

fbshipit-source-id: 433f5b624eaa5b4fb8b757ba0b503354d5da0623

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly