selftests/landlock: Remove unused macros in ptrace_test.c

After reviewing the code, it was found that these macros are never
referenced in the code. Just remove them.

Signed-off-by: Ba Jing <bajing@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20241118042407.12900-1-bajing@cmss.chinamobile.com


[mic: Reword subject]
Signed-off-by: Mickaël Salaün <mic@digikod.net>