Remove unused plot-area-min-clock-period.py

One-off ad-hoc plotting script for some discussion post,
not since maintained.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

Author: oharboe