Please remove "Lock screen before sleep" setting in session settings

Power manager uses the same setting. It should be power manager's setting, and it can be changed in xfce4-power-manager-settings.

It is better that user can choose each time whether to use lock or not, when he/she suspends manually. I am used to disabling this setting and use launcher for xflock4 && xfce4-session-logout --suspend that I use when I want to lock in conjunction with sleep. That also works better than suspending by e.g. Action Buttons due to bugs like #15 (moved). and #108 (closed).

Unfortunately, if I disable the setting in session settings, I do not have an option to lock when power manager puts system to sleep (besides power manager has similar issues xfce4-power-manager#5 (closed) and xfce4-power-manager#127 (moved)).