ANDROID: uid_sys_stats: Drop CONFIG_UID_SYS_STATS_DEBUG logic

It was pointed out that since commit b6115e14 ("ANDROID:
uid_sys_stat: split the global lock uid_lock to the fine-grained locks
for each hlist in hash_table") taking a spin_lock in uid_lock()
causes a scheduling while atomic error if CONFIG_UID_SYS_STATS_DEBUG
is enabled, as get_full_task_comm() takes the mmap_write_lock()
which is a semaphore, breaking the proper ordering.

In the GKI CONFIG_UID_SYS_STATS_DEBUG is disabled, so this went
unnoticed.

The uid_sys_stats logic isn't ever going to go upstream (it depends
on reverting upstream logic) and will hopefully be replaced eventually.
So there's not much reason to drag around this debug logic that is
unused.

So drop it. Less code to schlep forward.

Bug: 320184870
Change-Id: I2cfce79d5a25a3eba11a5509444c07b4642ef2de
Signed-off-by: John Stultz <jstultz@google.com>