Added two more tests for multiple and no api-endpoints

Added two more api-endpoint test cases for multiple endpoints (and using only the first one) and no endpoints (so automatically refresh and return the first endpoint then).
Seems a fair point. What if we just simplify all of it to a simple "setAPIAddresses". And then we can call it with an empty list, or with a known list.
We just move the call to s.APIInfo() a bit earlier, and then do:
s.setAPIAddresses(c, []string{info.Addrs[0], "0.1.2.3...", "0.1.2.3..."})