runtime: Set b:undo_ftplugin where missing (#12943)

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/ftplugin/scala.vim b/runtime/ftplugin/scala.vim
index b484df9..769499c 100644
--- a/runtime/ftplugin/scala.vim
+++ b/runtime/ftplugin/scala.vim
@@ -4,6 +4,7 @@
 " URL:                  https://github.com/derekwyatt/vim-scala
 " License:              Same as Vim
 " Last Change:          11 August 2021
+"                       2023 Aug 28 by Vim Project (undo_ftplugin)
 " ----------------------------------------------------------------------------
 
 if exists('b:did_ftplugin') || &cp
@@ -32,4 +33,6 @@
 setlocal path+=src/main/scala,src/test/scala
 setlocal suffixesadd=.scala
 
+let b:undo_ftplugin = "setlocal cms< com< et< fo< inc< inex< pa< sts< sua< sw<"
+
 " vim:set sw=2 sts=2 ts=8 et: