T6693: wireless: add missing country-code for 2.4GHz 802.11ax smoketest

Commit 6b57f03 ("T6693: wireless: Enable WiFi-6 (802.11ax) for 2.4GHz
AccessPoints") added a new smoketest which lacked the presence of setting the
country-code under the wifi interface, which is a bit different starting with
VyOS 1.5.

smoketest/scripts/cli/test_interfaces_wireless.py

@@ -313,6 +313,7 @@ def test_wireless_hostapd_he_2ghz_config(self):
         channel_set_width = '81'
 
         self.cli_set(self._base_path + [interface, 'ssid', ssid])
+        self.cli_set(self._base_path + [interface, 'country-code', country])
         self.cli_set(self._base_path + [interface, 'type', 'access-point'])
         self.cli_set(self._base_path + [interface, 'channel', channel])
         self.cli_set(self._base_path + [interface, 'mode', 'ax'])