remove buf_loaded check

As this causes issues (buf switching i.e tbufbnext/tbufprev) not working properly when nvim is opened with multiple files dbb3439982 (commitcomment-77092312)

lua/core/utils.lua

@@ -199,7 +199,7 @@ M.bufilter = function()
    local bufs = vim.t.bufs
 
    for i = #bufs, 1, -1 do
-      if not vim.api.nvim_buf_is_loaded(bufs[i]) then
+      if not vim.api.nvim_buf_is_valid(bufs[i]) then
          table.remove(bufs, i)
       end
    end