fix: Handle non-location bound resources in region rotator (#881)

## Description

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Update the the PowerShell script to handle null resource locations (e.g
`consumption/budgets` returns `[]` to `Get-AzResourceProvider`)

## Testing


[![avm.res.consumption.budget](https://github.com/ChrisSidebotham/bicep-registry-modules/actions/workflows/avm.res.consumption.budget.yml/badge.svg?branch=csidebotham%2Fnon-loc-resource-handling)](https://github.com/ChrisSidebotham/bicep-registry-modules/actions/workflows/avm.res.consumption.budget.yml)

[![avm.res.network.dns-zone](https://github.com/ChrisSidebotham/bicep-registry-modules/actions/workflows/avm.res.network.dns-zone.yml/badge.svg?branch=csidebotham%2Fnon-loc-resource-handling)](https://github.com/ChrisSidebotham/bicep-registry-modules/actions/workflows/avm.res.network.dns-zone.yml)

avm/utilities/pipelines/e2eValidation/regionSelector/Get-AzAvailableResourceLocation.ps1

@@ -71,7 +71,7 @@ function Get-AzAvailableResourceLocation {
   $ResourceRegionList = (Get-AzResourceProvider | Where-Object { $_.ProviderNamespace -eq $formattedResourceProvider }).ResourceTypes | Where-Object { $_.ResourceTypeName -eq $formattedServiceName } | Select-Object -ExpandProperty Locations
   Write-Verbose "Region list: $($resourceRegionList | ConvertTo-Json)"
 
-  if ($resourceRegionList -eq "global") {
+  if ($resourceRegionList -eq "global" -or $null -eq $resourceRegionList) {
     Write-Verbose "Resource is global, default region [$GlobalResourceGroupLocation] will be used for resource group creation"
     $location = $GlobalResourceGroupLocation # Set Location to resource group location. Globabl resources should have hardocded location in `main.bicep`
   }