Create a new string to alert unsupported vpn start.

Test: Manual test
Change-Id: Ic32db48671335a59c3bf8b43065cfef7c39c2936

src/com/android/settings/vpn2/ConfigDialogFragment.java

@@ -209,8 +209,8 @@ public class ConfigDialogFragment extends InstrumentedDialogFragment implements
                 Toast.makeText(mContext, R.string.vpn_no_network, Toast.LENGTH_LONG).show();
             } catch (UnsupportedOperationException e) {
                 Log.e(TAG, "Attempted to start an unsupported VPN type.");
-                final AlertDialog dialog = new AlertDialog.Builder(mContext)
-                        .setMessage(R.string.vpn_insecure_dialog_subtitle)
+                final AlertDialog unusedDialog = new AlertDialog.Builder(mContext)
+                        .setMessage(R.string.vpn_start_unsupported)
                         .setPositiveButton(android.R.string.ok, null)
                         .show();
             }