Since "sculpt: adjust nitpicker priority", the nitpicker GUI server no
longer runs at the highest priority, yet the runtime_view of the
leitzentrale UI continued to operate at the highest priority.
On slower machines, this results in a visible interference of the CPU-
heavy rendering of the runtime_view with the (now) lower-prioritized
nitpicker, in particular laggy pointer movements.
This commit subordinates the leitzentrale components below the priority
of nitpicker to prevent this interference.
It also simplifies the priority scheme at the static system init: The
timer has the highest priority whereas all other components use the
priority band -1.
Issue #5174
edaff9fb96