python/machine: remove unused sock_dir argument

By using a socketpair for all of the sockets managed by the VM class and
its extensions, we don't need the sock_dir argument anymore, so remove
it.

We only added this argument so that we could specify a second, shorter
temporary directory for cases where the temp/log dirs were "too long" as
a socket name on macOS. We don't need it for this class now. In one
case, avocado testing takes over responsibility for creating an
appropriate sockdir.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20230928044943.849073-7-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

tests/avocado/machine_aspeed.py

@@ -247,7 +247,10 @@ class AST2x00Machine(QemuSystemTest):
         image_path = self.fetch_asset(image_url, asset_hash=image_hash,
                                       algorithm='sha256')
 
-        socket = os.path.join(self.vm.sock_dir, 'swtpm-socket')
+        # force creation of VM object, which also defines self._sd
+        vm = self.vm
+
+        socket = os.path.join(self._sd.name, 'swtpm-socket')
 
         subprocess.run(['swtpm', 'socket', '-d', '--tpm2',
                         '--tpmstate', f'dir={self.vm.temp_dir}',