Fix block_migration parameter in function live_migration
for _live_migrate_server in test_network_basic_ops

Related-prod: PRODX-35782
Change-Id: I24cd3982ec388ab5bc9850829c22aa03292dd99d
diff --git a/tempest/scenario/test_network_basic_ops.py b/tempest/scenario/test_network_basic_ops.py
index 90d249f..474db75 100644
--- a/tempest/scenario/test_network_basic_ops.py
+++ b/tempest/scenario/test_network_basic_ops.py
@@ -403,7 +403,7 @@
 
         self.os_adm.servers_client.live_migrate_server(
             server_id=server['id'],
-            block_migration=False,
+            block_migration=True,
             host=host_id)
 
         waiters.wait_for_server_status(