runtime(dockerfile): do not set commentstring in syntax script

fixes: #16268

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/dockerfile.vim b/runtime/syntax/dockerfile.vim
index 6ec71fc..f1d612f 100644
--- a/runtime/syntax/dockerfile.vim
+++ b/runtime/syntax/dockerfile.vim
@@ -1,6 +1,6 @@
 " dockerfile.vim - Syntax highlighting for Dockerfiles
 " Maintainer:   Honza Pokorny <https://honza.ca>
-" Last Change:  2024 Jul 03
+" Last Change:  2024 Dec 20
 " License:      BSD
 
 " https://docs.docker.com/engine/reference/builder/
@@ -35,7 +35,6 @@
 syntax region dockerfileValue  contained keepend start=/\v/ skip=/\v\\\_./ end=/\v$/ contains=dockerfileString
 
 syntax region dockerfileComment start=/\v^\s*#/ end=/\v$/ contains=@Spell
-set commentstring=#\ %s
 
 hi def link dockerfileString String
 hi def link dockerfileKeyword Keyword