fix(emqx_mgmt_cli): idempontent kick. now it always returns ok

apps/emqx_management/src/emqx_mgmt_cli.erl

@@ -142,10 +142,8 @@ clients(["show", ClientId]) ->
     if_client(ClientId, fun print/1);
 
 clients(["kick", ClientId]) ->
-    case emqx_cm:kick_session(bin(ClientId)) of
-        ok -> emqx_ctl:print("ok~n");
-        _ -> emqx_ctl:print("Not Found.~n")
-    end;
+    ok = emqx_cm:kick_session(bin(ClientId)),
+    emqx_ctl:print("ok~n");
 
 clients(_) ->
     emqx_ctl:usage([{"clients list",            "List all clients"},