OpenAPI: Revert changes from PR #42

[RoshniNaveenaS]

As per the discussion for the issue , reverting the change of appending the protocol and serviceName.

The URLs provided via command line options --openapi:url or --openapi:servers should be taken literally without appending protocol and service name.

These URLs tell where the service is deployed, and CAP should not make any assumptions on the deployment URL, nor impose any path conventions on how applications want to deploy their CAP microservice.

If none of these command line options is provided, the default URL of course needs to match the default URL of the CAP runtime, which now includes protocol and service name.