Description of problem: If we modify the quota and set lower value than actual it should not allow which can't be witnessed for subnets and octavia Version-Release number of selected component (if applicable): RHOSP16.1 Actual results: Can set lower quota for subnet than actual created Expected results: Should not be able to lower the quota Additional info: Details in bug https://bugzilla.redhat.com/show_bug.cgi?id=1977719