perf test: Use ARRAY_SIZE for array length

Use of macro ARRAY_SIZE to calculate array size minimizes
the redundant code and improves code reusability.

  ./tools/perf/tests/demangle-java-test.c:31:34-35: WARNING: Use ARRAY_SIZE.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=11173


Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240929093045.10136-1-jiapeng.chong@linux.alibaba.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>