fix: correctly create User autocmd in action.which_key (#2736)

(cherry picked from commit 550055e640)

lua/telescope/actions/init.lua

@@ -1270,7 +1270,8 @@ actions.which_key = function(prompt_bufnr, opts)
   -- only set up autocommand after showing preview completed
   if opts.close_with_action then
     vim.schedule(function()
-      vim.api.nvim_create_autocmd("User TelescopeKeymap", {
+      vim.api.nvim_create_autocmd("User", {
+        pattern = "TelescopeKeymap",
         once = true,
         callback = function()
           pcall(vim.api.nvim_win_close, km_win_id, true)