fix(lsp): unwanted redraw for buffer not in window #40002

Problem:  Redrawing when a loaded buffer is not shown in any window on
          the current tabpage.
Solution: Check that buffer is shown in a (normal) window before redrawing.

runtime/lua/vim/diagnostic.lua

@@ -1143,7 +1143,7 @@ end
 nvim_on('DiagnosticChanged', api.nvim_create_augroup('nvim.diagnostic.status', {}), {
   desc = 'diagnostics component for the statusline',
 }, function(ev)
-  if api.nvim_buf_is_loaded(ev.buf) then
+  if vim.fn.win_gettype(vim.fn.bufwinid(ev.buf)) == '' then
     api.nvim__redraw({ buf = ev.buf, statusline = true })
   end
 end)