storage_account: Fix Azure Germany ATP matching

Although the error message returned from Azure Germany Cloud is
precisely "The resource namespace 'Microsoft.Security' is invalid."
the error message we are seeing in `r/storage_account` has other
contents added on it, so we cannot do an equals check directly.
The ATP fix was being pushed as v1.36.0, but this change provides
the actual resolution.

Ref hashicorp#4563, hashicorp#4564.

azurerm/resource_arm_storage_account.go

@@ -1134,7 +1134,7 @@ func resourceArmStorageAccountRead(d *schema.ResourceData, meta interface{}) err
 	atp, err := advancedThreatProtectionClient.Get(ctx, d.Id())
 	if err != nil {
 		msg := err.Error()
-		if msg != "The resource namespace 'Microsoft.Security' is invalid." {
+		if !strings.Contains(msg, "The resource namespace 'Microsoft.Security' is invalid.") {
 			if !strings.Contains(msg, "No registered resource provider found for location '") {
 				if !strings.Contains(msg, "' and API version '2017-08-01-preview' for type ") {
 					return fmt.Errorf("Error reading the advanced threat protection settings of AzureRM Storage Account %q: %+v", name, err)