feat: source node pools' auto_upgrade configuration from the GKE default config

[MrwanBaghdad]

Allows the module to use the default_auto_upgrade to infer if the auto_upgrade is enabled for the node pool. This is in line with how the auto_upgrade config is calculated in the node_pool resource

  management {
    auto_repair  = lookup(each.value, "auto_repair", true)
    auto_upgrade = lookup(each.value, "auto_upgrade", local.default_auto_upgrade)
  }

[comment-bot-dev]

Thanks for the PR! 🚀
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[MrwanBaghdad]

@bharathkkb Can you please take a look?

[bharathkkb]

Thanks for the PR @MrwanBaghdad