Query only one event at the beginning (to find the ID of the latest event)

Syncthing's official web UI also does the first query for events like this.
This should make loading times a bit faster and removes the possibility of
picking-up obsolete events (which was always problematic).

connector/syncthingconnection_requests.cpp

@@ -1507,6 +1507,8 @@ void SyncthingConnection::requestEvents()
     QUrlQuery query;
     if (m_lastEventId) {
         query.addQueryItem(QStringLiteral("since"), QString::number(m_lastEventId));
+    } else {
+        query.addQueryItem(QStringLiteral("limit"), QStringLiteral("1"));
     }
     // force to return immediately after the first call
     if (!m_hasEvents) {