Use atomic discards for the operational DS

Port away from sysrepo::Connection::discardOperationalChanges() because
sysrepo now supports discarding via the usual sr_edit_batch(), yay.

The actual changes are slightly different, some high-level leaf-list
instances for example are apparently not reported.

Change-Id: I3c4f7e5aabe65c52f557c4cd060e0a6fbc316e16
Depends-on: https://gerrit.cesnet.cz/c/CzechLight/dependencies/+/6243
Depends-on: https://gerrit.cesnet.cz/c/CzechLight/sysrepo-ietf-alarms/+/6248
diff --git a/src/system/IETFSystem.cpp b/src/system/IETFSystem.cpp
index 8595465..5439d09 100644
--- a/src/system/IETFSystem.cpp
+++ b/src/system/IETFSystem.cpp
@@ -132,7 +132,7 @@
         {IETF_SYSTEM_STATE_MODULE_PREFIX + "platform/os-version", osReleaseContents.at("VERSION")},
     };
 
-    utils::valuesPush(opsSystemStateData, {}, m_srSession, sysrepo::Datastore::Operational);
+    utils::valuesPush(opsSystemStateData, {}, {}, m_srSession, sysrepo::Datastore::Operational);
 }
 
 void IETFSystem::initSystemRestart()
@@ -222,7 +222,7 @@
             values[IETF_SYSTEM_DNS_PATH + "/server[name='"s + e + "']/udp-and-tcp/address"] = e;
         }
 
-        utils::valuesToYang(values, {}, session, parent);
+        utils::valuesToYang(values, {}, {}, session, parent);
         return sysrepo::ErrorCode::Ok;
     };