socket: rework to match docs more closely, improve accuracy on linux (#11219)

Match the documentation more closely

Fixes some of #8101

tests/stubtest_allowlists/py3_common.txt

@@ -198,7 +198,6 @@ xml.sax.expatreader
 # Module members that exist at runtime, but are missing from stubs
 # ==========
 _json.encode_basestring
-_socket.CAPI
 _thread.LockType.acquire_lock
 _thread.LockType.locked_lock
 _thread.LockType.release_lock
@@ -249,7 +248,6 @@ multiprocessing.managers.SyncManager.Pool
 multiprocessing.pool.Pool.Process
 multiprocessing.pool.ThreadPool.Process
 multiprocessing.synchronize.Semaphore.get_value
-socket.CAPI
 tkinter.Misc.config
 tkinter.font.Font.counter
 tkinter.tix.CObjView