tests: Replace the O_RDONLY in access(2).

Although O_RDONLY gives the same value as F_OK (0), it's not the right
friend of access(2).

Also clean up the temporary files from ZipTest (TemporaryDir doesn't
like non-empty directory).

Test: recovery_unit_test passes and has no leftover.
Change-Id: I66b90e43c0954c89ce08b36b9e2b4e84183b28f5