tool/sched_ext: Event counter dumping updates

tool/sched_ext: Event counter dumping updates

- There's no need to dump event counters from both scx_qmap and scx_central.
  Drop counter dumping from scx_central.

- bpf_printk() implies a trailing new line and the explicit new line leads
  to double new lines. Drop the explicit new lines.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Changwoo Min <changwoo@igalia.com>