fix: report an error when the node template is not found

[tzneal]

Fixes #4698

Description

Without this change, no instance types are found and the resulting behavior is a generic error regarding not finding instance types.

How was this change tested?

Deployed to EKS with no node template.

Previous error message:

INFO	controller.provisioner	provisioning/provisioner.go:238	skipping, no resolved instance types found	
ERROR	controller.provisioner	scheduling/scheduler.go:190	Could not schedule pod, all available instance types exceed limits for provisioner: "default"	

New Error Message

karpenter-5cd78bcc87-jlwnp controller 2023-09-28T12:49:09.907Z	ERROR	controller.provisioner	creating scheduler, getting instance types, resolving node class, resolving node template, getting providerRef, AWSNodeTemplate.karpenter.k8s.aws "defaultFake" not found	{"commit": "d71c265-dirty"

kubernetes-sigs/karpenter#547 modifies karpenter-core to log the instance type failure, but continue on to the next provisioner, changing the error into:

karpenter-d7887b4d7-wx64q controller 2023-09-28T13:04:14.064Z	ERROR	controller.provisioner	skipping, unable to resolve instance types, resolving node class, resolving node template, getting providerRef, AWSNodeTemplate.karpenter.k8s.aws "defaultFake" not found	{"commit": "ff540d0", "provisioner": "default"}
karpenter-d7887b4d7-wx64q controller 2023-09-28T13:04:14.066Z	ERROR	controller.provisioner	Could not schedule pod, all available instance types exceed limits for provisioner: "default"	{"commit": "ff540d0", "pod": "default/inflate-54b8bcf56d-fq8kk"}

Does this change impact docs?

• Yes, PR includes docs updates
• Yes, issue opened: #
• No

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

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[jonathan-innis]

LGTM 🚀