selftests/landlock: Fix snprintf truncation checks in audit helpers

selftests/landlock: Fix snprintf truncation checks in audit helpers

snprintf() returns the number of characters that would have been
written, excluding the terminating NUL byte.  When the output is
truncated, this return value equals or exceeds the buffer size.  Fix
matches_log_domain_allocated() and matches_log_domain_deallocated() to
detect truncation with ">=" instead of ">".

Cc: Günther Noack <gnoack@google.com>
Cc: stable@vger.kernel.org
Fixes: 6a500b22971c ("selftests/landlock: Add tests for audit flags and domain IDs")
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20260402192608.1458252-2-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>