[CX] rebalance failure on cancelled initial topology change

[ns_server:debug,2020-06-19T08:46:34.864-07:00,n_0@127.0.0.1:cleanup_process<0.1427.0>:service_janitor:maybe_init_topology_aware_service:80]Doing initial topology change for service `cbas'

...

[ns_server:debug,2020-06-19T08:46:34.878-07:00,n_0@127.0.0.1:cleanup_process<0.1427.0>:service_janitor:do_orchestrate_initial_rebalance:123]Received exit message {'EXIT',<0.1199.0>,shutdown}. Terminating initial rebalance

[ns_server:error,2020-06-19T08:46:34.878-07:00,n_0@127.0.0.1:service_rebalancer-cbas<0.1433.0>:service_rebalancer:run_rebalance_worker:128]Got exit message from parent: {'EXIT',<0.1427.0>,shutdown}

[ns_server:error,2020-06-19T08:46:34.879-07:00,n_0@127.0.0.1:service_agent-cbas<0.1299.0>:service_agent:handle_info:287]Rebalancer <0.1433.0> died unexpectedly: shutdown