storage_service: Serialize more node management operations with read api lock
storage_service: Serialize more node management operations with read api lock

- get_operation_mode
- is_starting
- is_rpc_server_running
- is_native_transport_running
- get_load_map
- is_initialized

scylladb/scylla,raphaelsc/scylla,avikivity/scylla,raphaelsc/scylla,scylladb/scylla,kjniemi/scylla,scylladb/scylla,raphaelsc/scylla,avikivity/scylla,scylladb/scylla,kjniemi/scylla,kjniemi/scylla,duarten/scylla,avikivity/scylla,duarten/scylla,duarten/scylla