[sdk-platform-java] host is not updated when universe domain is specified

[JesseLovelace]

When a client specifies a universe domain, the host value does not get automatically updated to match. For example, if I create a storage client:

Storage storage = StorageOptions.grpc().setUniverseDomain("my-universe-domain.com").build().getService();

Then
storage.getOptions().getUniverseDomain() properly returns my-universe-domain, but storage.getOptions.getHost() just returns www.googleapis.com, when it should return https://storage.my-universe-domain.com