Improve feedback when GN cannot connect to service if not logged in

**Background**
In the downloads/links/etc. section of the metadata record page, anonymous users get to see something like this if GeoNetwork cannot connect to a service and its URL can therefore not be analyzed:


However, if you would log in to GeoNetwork, this message disappears and you get to see a `Download` button instead.

**Problem**
The `Unable to connect to service` message is unclear and falsely gives the impression that the URL cannot be reached and/or the service is down.

**Proposed solution**
In the case that the URL cannot be analyzed because the user is not logged in, instead of showing `Unable to connect to service`, change the message to `Please log in to connect to the service` or something like that.