fix(backup): validate Azure Files registration routing

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Bharat Purwar

src/azure-cli/azure/cli/command_modules/backup/custom_base.py

@@ -515,6 +515,9 @@ def register_container(cmd, client, vault_name, resource_group_name, workload_ty
     if workload_type is None:
         raise RequiredArgumentMissingError(
             "--workload-type is required with --backup-management-type AzureWorkload.")
+    if workload_type.lower() in ["azurefiles", "azurefileshare"]:
+        raise InvalidArgumentValueError(
+            "--workload-type AzureFileShare requires --backup-management-type AzureStorage.")
     if resource_id is None:
         raise RequiredArgumentMissingError(
             "--resource-id is required with --backup-management-type AzureWorkload.")

src/azure-cli/azure/cli/command_modules/backup/tests/latest/test_custom_afs.py

@@ -28,6 +28,12 @@ def test_register_container_rejects_afs_arguments_for_azure_workload(self):
                     Mock(), Mock(), "vault", "rg", "MSSQL",
                     resource_id="resource-id", **arguments)
 
+    def test_register_container_rejects_afs_workload_for_azure_workload(self):
+        with self.assertRaises(InvalidArgumentValueError):
+            custom_base.register_container(
+                Mock(), Mock(), "vault", "rg", "AzureFileShare",
+                resource_id="resource-id")
+
     @patch("azure.cli.command_modules.backup.custom_base.register_wl_container")
     def test_register_container_preserves_azure_workload_default(self, register_wl_container):
         cmd = Mock()