runtime(helpcurwin): fix E121 error

closes: #19270

Signed-off-by: Peter Kenny <github.com@k1w1.cyou>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/pack/dist/opt/helpcurwin/plugin/helpcurwin.vim

@@ -3,15 +3,9 @@ vim9script
 # Open Vim help on {subject} in the current window (rather than a new split)
 #
 # Maintainer:   The Vim Project <https://github.com/vim/vim>
-# Last change:  2025 Dec 02
+# Last change:  2026 Jan 29
 
-# Exit when the helpcurwin plugin is loaded already
-if exists('g:loaded_helpcurwin')
-  finish
-endif
-g:loaded_helpcurwin = true
-
-import autoload 'helpcurwin.vim'
+import autoload '../autoload/helpcurwin.vim'
 
 command -bar -nargs=? -complete=help HelpCurwin helpcurwin.Open(<q-args>)