gh-119461: Restore the testSocket VSOCK skipUnless removed by PR GH-119465 (GH-129561)
Restore the skipUnless removed by GH-119465.
This test can only pass on virtual machines, not actual machines.
actual machines see:
```
self.cli.connect((cid, VSOCKPORT))
~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
OSError: [Errno 19] No such device
```
Reproduced on (Linux) Ubuntu 24.04.1 running 6.8.0-52-generic.
(cherry picked from commit
e1006ce1ded1b18972888ef057718dba6f2c7edd)
Co-authored-by: Gregory P. Smith <greg@krypto.org>
@unittest.skipIf(WSL, 'VSOCK does not work on Microsoft WSL')
@unittest.skipUnless(HAVE_SOCKET_VSOCK,
'VSOCK sockets required for this test.')
+@unittest.skipUnless(get_cid() != 2, # VMADDR_CID_HOST
+ "This test can only be run on a virtual guest.")
class ThreadedVSOCKSocketStreamTest(unittest.TestCase, ThreadableTest):
def __init__(self, methodName='runTest'):