The timedate1_call will fail because network time synchronization is enabled:
GDBus.Error:org.freedesktop.timedate1.AutomaticTimeSyncEnabled: Automatic time synchronization is enabled
Let's not set_time when NTP is not available, neither set time by
accident at the widget construction stage. When widgets signals are connected
in the UI file their respective callback was getting called. By moving
the signal connection to callbacks to the widget's _init method we
avoid the unwanted callback call.
Fixes#2945