allow running the CSI controller outside DigitalOcean infrastructure

[thojkooi]

When running the CSI controller outside DO, it will still attempt to contact the metadata service due to it attempting to collect the droplet ID.

When running in controller mode, it will ignore the error from DropletID(). With this change, it fixes the "Controller only mode not in DigitalOcean" mentioned in the README file.

I could not find any references to hostID() except for some node related logic, which from what I could tell is not called when running in controller mode.

Signed-off-by: Thomas Kooi [email protected]