Revert "tests: --freelist-big-blocks=0"

This reverts commit ea893901e1445a4d37a7d56bb112927692e10862.
tests: don't collect log files

Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
tests: use different dir for each test case

Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>