It should be possible to indicate the managed service broker that a service should not be available

[maleck13]

Description

I am adding work to the installer to allow us to no longer need to install everything.
However when I no longer install threescale, I still see the 3scale service class in the catalog.
I think for the "dashboard" services if the url is empty then it should not create a service class

[maleck13]

@philbrookes @JameelB

[philbrookes]

this seems reasonable to me, and would be a simple bit of logic to add here: https://github.com/integr8ly/managed-service-broker/blob/master/pkg/deploys/threescale/deployer.go#L28