Remove flat_maps from our dbus parsing types

There's nowhere in the codebase where we actually use these as maps.
99% of the time, we just iterate and pull these into specific data
structures anyway, so there's no reason for them to be maps.

This saves a negligible amount (600 bytes) on our compressed binary
size.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I91085cfa2cf8d70e0f0fa0f2f3927776667d834f
diff --git a/include/dbus_utility.hpp b/include/dbus_utility.hpp
index 0ed0bbc..eefc115 100644
--- a/include/dbus_utility.hpp
+++ b/include/dbus_utility.hpp
@@ -63,8 +63,8 @@
 
 using ManagedItem = std::pair<
     sdbusplus::message::object_path,
-    boost::container::flat_map<
-        std::string, boost::container::flat_map<std::string, DbusVariantType>>>;
+    std::vector<std::pair<
+        std::string, std::vector<std::pair<std::string, DbusVariantType>>>>>;
 
 // Map of service name to list of interfaces
 using MapperServiceMap =