client: Don't auto register agent on non-interactive mode

There is no use to register an agent when on non-interactive mode.
diff --git a/client/main.c b/client/main.c
index 38df758..962f338 100644
--- a/client/main.c
+++ b/client/main.c
@@ -520,7 +520,8 @@
 		if (!agent_manager) {
 			agent_manager = proxy;
 
-			if (auto_register_agent)
+			if (auto_register_agent &&
+					!bt_shell_get_env("NON_INTERACTIVE"))
 				agent_register(dbus_conn, agent_manager,
 							auto_register_agent);
 		}