This is taking about 15 seconds to fail if addr is on an existing network, not two seconds.

I recreated this method without headers and raise "omg #{se.inspect}" instead
```
irb(main):025:0> server_available?("192.168.5.120", 80)
omg #<Timeout::Error: execution expired>
=> false
```

In the past we've avoided calling the metadata server unless we have some proof it will be there because we don't want to risk adding multiple seconds of delay to Ohai for people on other networks. If the DMI hint is reliable, we should be able to avoid calling has_metadata? in #looks_like_gce.