Continue refactoring quota enforcer spec
Continue refactoring quota enforcer spec

* Added additional sub-contexts to enhance testing of catalog changes
* Used helper methods

[#67082390]

cloudfoundry/cf-mysql-broker,cloudfoundry/cf-mysql-broker,cloudfoundry/cf-mysql-broker,SudarsananRengarajan/cf-mysql-broker,SudarsananRengarajan/cf-mysql-broker