Extend xfconfd SHUTDOWN_TIMEOUT_SECONDS to match xfce4-panel requirements
xfconfd's predefined SHUTDOWN_TIMEOUT_SECONDS in xfconf-lifecycle-manager.c is 5 minutes, whereas xfce4-panel uses xfconfd to save its settings every 10 minutes. As a result, xfconfd is re-activated every 10 minutes and (I quote) "a tsunami of log spam" is generated needlessly. Could we please extend this timeout to 11 or 15 minutes and avoid all this spam? Thanks!