chore: bump aks sku from free to standard to address API server perfo… (

#1121)

## Description
We've been seeing consistent nightly ci failures on AKS that suggest
that the API server is a bottleneck to uds-core deployment.
From @mjnagel:
-
https://github.com/defenseunicorns/uds-core/actions/runs/12310537338/job/34359271873#step:11:320:
no error message but failed to reconcile authservice :thonk:
-
https://github.com/defenseunicorns/uds-core/actions/runs/12290831792/job/34298610444#step:11:292:
doesn't look like pepr picked up prometheus
-
https://github.com/defenseunicorns/uds-core/actions/runs/12308571271/job/34354169433?pr=1117#step:11:304:
Failed to apply network policies
([this](https://github.com/defenseunicorns/uds-core/blob/6426c5aaf75bcb761b27ca415cf5736631a72f85/src/pepr/operator/controllers/network/policies.ts#L155)
is where that error comes from)
-
https://github.com/defenseunicorns/uds-core/actions/runs/12308571271/job/34354169733?pr=1117#step:11:360:
more netpol failures + token failure

This PR bumps the cluster SKU from `Free` to `Standard` as there are
inflight request
[limits](https://learn.microsoft.com/en-us/azure/aks/quotas-skus-regions#:~:text=server/etcd%20instances.-,Free%20tier,-Limited%20resources%20with)
for `Free` tier clusters.
## Related Issue

Fixes #
<!-- or -->
Relates to #

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [x] Other (security config, docs update, etc)

## Steps to Validate
N/A

## Checklist before merging

- [ ] Test, docs, adr added or updated as needed
- [ ] [Contributor
Guide](https://github.com/defenseunicorns/uds-template-capability/blob/main/CONTRIBUTING.md)
followed

.github/test-infra/azure/aks/variables.tf

@@ -24,12 +24,12 @@ variable "dns_prefix" {
 }
 
 variable "sku_tier" {
-  description = "(Optional) The SKU Tier that should be used for this Kubernetes Cluster. Possible values are Free and Paid (which includes the Uptime SLA). Defaults to Free."
-  default     = "Free"
+  description = "(Optional) The SKU Tier that should be used for this Kubernetes Cluster. Possible values are Free and Standard (which includes the Uptime SLA), and Premium. Defaults to Free."
+  default     = "Standard"
   type        = string
 
   validation {
-    condition     = contains(["Free", "Paid"], var.sku_tier)
+    condition     = contains(["Free", "Standard", "Premium"], var.sku_tier)
     error_message = "The sku tier is invalid."
   }
 }