Fix node_count default

[rbren]

Was working with EJ and noticed that after running pentagon start-project and runner cluster_configure, the file inventory/default/clusters/$cluster/cluster-config/nodes.yml had three InstanceGroups with maxSize=minSize=3, resulting in a total of 9 nodes (3 per subnet), rather than the desired 3 nodes (1 per subnet). From what I understand, we recently switched from having one IG spread across 3 subnets, to one IG per subnet - guessing this is an artifact of that change.

Changing this default sets ig_max_size=ig_min_size=1 in inventory/default/clusters/$cluster/vars.yml, which results in maxSize=minSize=1 in nodes.yml.

Let me know if there's a better way to fix this.

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[sudermanjr]

I would love to see a change where the initial maxSize is set to a higher number than 1. As it is right now, we have to make a change to enable autoscaling.

As it stands, this PR seems fine. Maybe open an issue for the rest?

[ejether]

Agreed, but I think that will be a more substantial change. @bobby-brennan woud you drop a note in the CHANGELOG.md about the change?

[rbren]

Done - bumped version to 3.1.2 as well.