Fix multiple lock screen buttons
Originally created by @segfault on #12449 (Redmine)
anonym reported that he saw multiple lock screen buttons in the GNOME
status menu during multiple testing sessions: #5684 (closed)-57 #5684 (closed)-63
#5684 (closed)-64
I was not able to reproduce this issue.
Parent Task: #5684 (closed)
Edited by segfault