Bug: X-Svdx-Hostname header value is incorrect in some deployment setups

If the service is deployed at its own domain like https://mysvdx.com, this bug is not occurring. That's the reason we haven't caught it so far, as our test deployment has two svdx instances on two different domains.

However, if the service is deployed at a domain and is referenced on a subpath, like for example: https://mycluster.com/svdx then a bug happens when the X-SVDX-HOSTNAME header is set, because it only contains the base domain mycluster.com. This means that OCM/PCM later cannot make requests to the SVDX endpoints because they don't know anything about the subpath component.

Fix that by setting a correct value in this header.