pbench-metadata-log: heavy-handed behavior with hostnames

[ndokos]

There are valid cases where the controller and remotes have names that are not the ones that hostname -s or hostname -f return. For example, nodes with multiple interfaces (one on a Gb lab network, with its IP address associated with the "official" hostname, and one with a 10Gb test network with an ad-hoc name) are often used in openstack (and other) testing. In such cases, the ad-hoc names are used as pbench remotes. pbench-metadata-log insists on using the official name in such cases (because that is what appears in sos reports and is used to associate the sos report information with the host for indexing), but it is a bit heavy-handed in that it also tries to use the official name to do ssh/scp and gather some data from the remote host. That fails, since that translates to the lab network, which in some cases at least cannot reach the remote hosts.

We need the official name in the metadata log, but we should not use it to try to reach the remotes if a different name was specified.

Reported by @wilkins11.