autotest: network_VPNConnect: Use ConfigureService rather than GetService

This test has always used GetService to configure the VPNService. Fix
this before removing the Manager::GetService VPN hack in Shill.

BUG=chromium:213802
TEST=`test_that $DUT network_VPNConnect.l2tpipsec_psk`

Change-Id: I851627152bf630abfab58f53a8430f6e0a2a447f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2037668
Commit-Queue: Alex Khouderchah <akhouderchah@chromium.org>
Tested-by: Alex Khouderchah <akhouderchah@chromium.org>
Reviewed-by: Eric Caruso <ejcaruso@chromium.org>
diff --git a/client/site_tests/network_VPNConnect/network_VPNConnect.py b/client/site_tests/network_VPNConnect/network_VPNConnect.py
index 78f827e..01dd24e 100644
--- a/client/site_tests/network_VPNConnect/network_VPNConnect.py
+++ b/client/site_tests/network_VPNConnect/network_VPNConnect.py
@@ -177,7 +177,8 @@
         """Connects the client to the VPN server."""
         proxy = self._shill_proxy
         with tpm_store.TPMStore() as tpm:
-            service = proxy.get_service(self.get_vpn_client_properties(tpm))
+            service = proxy.configure_service(
+                self.get_vpn_client_properties(tpm))
             service.Connect()
             result = proxy.wait_for_property_in(service,
                                                 proxy.SERVICE_PROPERTY_STATE,