Use show_quota_class_set after update_quota_class_set

In test_update_default_quotas, we should use show_quota_class_set
after update_quota_class_set to check whether the quota values
are really changed.
Besides, some LOG messages look odd and maybe being used as comments
are more suitable.

Change-Id: I05e22c88e184df7d425411051c2a8bf846cb35ee
1 file changed