Consitently use dbus::utility types

This saves about 4k on the binary size

Tested: Redfish service validator passes.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I9546227a19c691b1aecb80e80307889548c0293f
diff --git a/include/nbd_proxy.hpp b/include/nbd_proxy.hpp
index afb6493..e0a0111 100644
--- a/include/nbd_proxy.hpp
+++ b/include/nbd_proxy.hpp
@@ -261,10 +261,8 @@
 
             auto getUserInfoHandler = [&conn, asyncResp](
                                           const boost::system::error_code ec,
-                                          boost::container::flat_map<
-                                              std::string,
-                                              dbus::utility::DbusVariantType>
-                                              userInfo) {
+                                          const dbus::utilities::
+                                              DBusPropertiesMap& userInfo) {
                 if (ec)
                 {
                     BMCWEB_LOG_ERROR << "GetUserInfo failed...";