Fix for v2 instance creation types

[ddymko]

Description

With API v2 there was a change that no longer requires the passing of os_id with snapshot, app, or iso.

Packer was still adding in the corresponding os_id with the other types so this PR will remove that.

I tested creation of snapshot, app, os, and iso independently. @Oogy you mind going through these builds also.

Related Issues

fixes #105

Checklist:

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