Babel option for Vietnamese is called "vietnamese"

The renaming happened in 2013. Contrary to what is stated in the
babel-vietnamese manual, option "vietnam" does not work anymore.

Also, the special care is not needed anymore, since language options
are not hardcoded anymore in babel.

Fixes: #10743

lib/languages

@@ -1095,17 +1095,13 @@ End
 #	LangCode         ur_PK
 #End
 
-# vietnam must be loaded locally with babel options,
-# not globally via class options, see
-# http://www.mail-archive.com/lyx-devel@lists.lyx.org/msg129417.html
 Language vietnamese
 	GuiName          "Vietnamese"
-	BabelName        vietnam
+	BabelName        vietnamese
 	PolyglossiaName  vietnamese
 	QuoteStyle       french
 	Encoding         utf8
 	LangCode         vi_VN
-	AsBabelOptions   true
 	Requires         vietnamese
 End
 

status.22x

@@ -60,6 +60,10 @@ What's new
 - Assure the color package is loaded before polyglossia in preview snippets
   This fixes preview image generation with polyglossia and bidi (bug 10716).
 
+- Fix babel name of Vietnamese language. This requires now babel-vietnamese
+  (2013ff.) instead of vietnam.ldf that was shipped with vntex previously
+  (bug 10743).
+
 
 * LYX2LYX