fix: downgrade Azure IMDS required version

Fixes siderolabs#8555

It seems that older version supports same set of fields we actually use
in our platform code, so we can safely downgrade to the version
supported by Azure Stack Hub.

I used
[this repo](https://github.com/Azure/azure-rest-api-specs/tree/main/specification/imds/data-plane/Microsoft.InstanceMetadataService/stable)
to check schemas across versions.

Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>

internal/app/machined/pkg/runtime/v1alpha1/platform/azure/metadata.go

@@ -19,11 +19,11 @@ const (
 	// https://blogs.msdn.microsoft.com/mast/2015/05/18/what-is-the-ip-address-168-63-129-16/
 	AzureInternalEndpoint = "http://168.63.129.16"
 	// AzureMetadataEndpoint is the local endpoint for the metadata.
-	AzureMetadataEndpoint = "http://169.254.169.254/metadata/instance/compute?api-version=2021-12-13&format=json"
+	AzureMetadataEndpoint = "http://169.254.169.254/metadata/instance/compute?api-version=2020-06-01&format=json"
 	// AzureInterfacesEndpoint is the local endpoint to get external IPs.
-	AzureInterfacesEndpoint = "http://169.254.169.254/metadata/instance/network/interface?api-version=2021-12-13&format=json"
+	AzureInterfacesEndpoint = "http://169.254.169.254/metadata/instance/network/interface?api-version=2020-06-01&format=json"
 	// AzureLoadbalancerEndpoint is the local endpoint for load balancer config.
-	AzureLoadbalancerEndpoint = "http://169.254.169.254/metadata/loadbalancer?api-version=2021-05-01&format=json"
+	AzureLoadbalancerEndpoint = "http://169.254.169.254/metadata/loadbalancer?api-version=2020-06-01&format=json"
 
 	mnt = "/mnt"
 )