shared/shell: Do not quit immediatelly on noninteractive mode

The command handler shall be able to tell when it is done by calling
bt_shell_noninteractive_quit.
diff --git a/src/shared/shell.c b/src/shared/shell.c
index f1e87d0..1fec58d 100644
--- a/src/shared/shell.c
+++ b/src/shared/shell.c
@@ -966,10 +966,7 @@
 			return true;
 		}
 
-		if (!data.timeout) {
-			bt_shell_detach();
-			mainloop_quit();
-		} else
+		if (data.timeout)
 			timeout_add(data.timeout * 1000, shell_quit, NULL,
 								NULL);
 	}