network_manager: Reloads should be delayed via timer

Our restarts of systemd waited a short amount of time (3s) prior to
triggering in the past and didn't cause it to reconfigure immediately.
This allowed lan users to queue up a bunch of configuration commands
that would reconfigure the network before it applied.

This patch restores that behavior.

Change-Id: I4c3c589c07528a9d90e6d7e5d3b649688fcf4587
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/network_manager.cpp b/src/network_manager.cpp
index b8fcaab..19e4673 100644
--- a/src/network_manager.cpp
+++ b/src/network_manager.cpp
@@ -35,7 +35,7 @@
 namespace network
 {
 
-extern std::unique_ptr<Timer> refreshObjectTimer;
+extern std::unique_ptr<Timer> reloadTimer;
 using namespace phosphor::logging;
 using namespace sdbusplus::xyz::openbmc_project::Common::Error;
 
@@ -255,6 +255,11 @@
 
 void Manager::reloadConfigs()
 {
+    reloadTimer->restartOnce(reloadTimeout);
+}
+
+void Manager::doReloadConfigs()
+{
     for (auto& hook : reloadPreHooks)
     {
         try