Remove InitDB functionality, rely on metal-api / metalctl apply instead

[majst01]

The current approach of creating initial tenant and project entities is weird and counter intuitive.

We should instead expose all CRUD api endpoints for tenant and project in metal-api and then we can create initial entities with metalctl apply -f.

@Gerrit91 Thoughts ?

[Gerrit91]

Yes, let's remove this mechanism if possible. metal-api should be able to handle this.

[majst01]

Required PR metal-stack/metal-api#357