Move to common variant

This saves approximately 34kB in the compressed binary size of bmcweb
due to reduced template instantiations.  This amounts to a 2.5%
reduction in the overall size.

Note, there were a few places where we broke const-correctness in the
form of pulling a non-const reference out of a const variant.  This
new variant now requires const correctness, so some consts are
added where required.

Tested: Code compiles.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I6a60c8881c1268627eedb4ffddf16689dc5f6ed2
diff --git a/redfish-core/lib/telemetry_service.hpp b/redfish-core/lib/telemetry_service.hpp
index b79a5cd..c3082d7 100644
--- a/redfish-core/lib/telemetry_service.hpp
+++ b/redfish-core/lib/telemetry_service.hpp
@@ -3,10 +3,9 @@
 #include "utils/telemetry_utils.hpp"
 
 #include <app.hpp>
+#include <dbus_utility.hpp>
 #include <registries/privilege_registry.hpp>
 
-#include <variant>
-
 namespace redfish
 {
 
@@ -27,9 +26,10 @@
         "/redfish/v1/TelemetryService/Triggers";
 
     crow::connections::systemBus->async_method_call(
-        [asyncResp](const boost::system::error_code ec,
-                    const std::vector<std::pair<
-                        std::string, std::variant<uint32_t, uint64_t>>>& ret) {
+        [asyncResp](
+            const boost::system::error_code ec,
+            const std::vector<
+                std::pair<std::string, dbus::utility::DbusVariantType>>& ret) {
             if (ec == boost::system::errc::host_unreachable)
             {
                 asyncResp->res.jsonValue["Status"]["State"] = "Absent";