bus_cgroup_set_tasks_max_scale() used a hand-rolled percentage format
that produced values ~10x too small (e.g., "TasksMax=4.0%" instead of
"TasksMax=40.00%").
On daemon-reload, the incorrect value was re-read, silently reducing
the effective TasksMax by ~10x and causing fork rejections on systems
with high thread counts.
Fix by using the existing PERMYRIAD macros, consistent with memory
property handlers (MemoryMax, MemoryHigh, MemoryLow, etc.).
Fixes: #41009
Cyrus Xi
9d15e09d5c