Update generate-deployment-manifest to refer to cf-stubs
Update generate-deployment-manifest to refer to cf-stubs

Yesterday, partially based on these instructions, I accidentally gave `generate-deployment-manifest` my actual cf-release manifest. I don't think that's what we want here. In cf-mysql-release we provide a `cf-stub.yml` which an operator should be providing for both (I think) bosh-lite and IaaS-based invocations of `generate-deployment-manifest`?

[#114036369]
cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release