CreateNodesWithGroupEncodedIntoNameThenAddToSet.getNextNames spams API requests

[abayer]

It's particularly bad if (a) you have a lot of instances in the account you're using on the provider, since the listNodes call ends up big and may be paged, and/or (b) you're creating a bunch of instances in separate groups at roughly the same time (for example, to work around #1469 if you need more granular control over your instance names), you end up with a ton of calls, one per group.

It'd be nice if this wasn't so chatty, to say the least. =)