TS-1909: remove duplicate listen socket conditioning

Socket options were applied to the listen sockets in both
Server::setup_fd_for_listen() and Server::listen(). There's really
only a need for one of these, so remove all the duplicated code.
Revert "TS-1909: remove duplicate listen socket conditioning"

This reverts commit 03cbafef3ce88c4fe39f866532f212a4da820afa. This
seems to be causing failures in the following regression tests:
SDK_API_HttpAltInfo, SDK_API_HttpTxnTransform, SDK_API_HttpTxnCache,
SDK_API_HttpSsn and SDK_API_HttpHookAdd.
TS-1909: remove duplicate listen socket conditioning

Socket options were applied to the listen sockets in both
Server::setup_fd_for_listen() and Server::listen(). There's really
only a need for one of these, so remove all the duplicated code.