update create dir testcase related to the related to incorrect value change

[princeparmar]

need to update system-test check in create dir

system_test/tests/cli_tests/zboxcli_create_dir_test.go

Line 38 in c9af564

require.Contains(t, []int{6, 8}, dir.Size, "Directory is not of size 6 or 8: %v", dir)

as we have removed the default size from blobber. which was incorrect value

Blobber issue: 0chain/blobber#329
Blobber PR: 0chain/blobber#491

[princeparmar]

@cnlangzi https://github.com/0chain/blobber/runs/4722602816?check_suite_focus=true