bug: long_message_to_split and cmdline_output_to_split presets don't work when custom routes are defined

[Subjective]

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Neovim version (nvim -v)

NVIM v0.10.0-dev-546+g3bf887f6e

Operating system/version

MacOS 13.3

Describe the bug

When custom routes are defined in the setup table, the presets long_message_to_split and cmdline_output_to_split don't do anything even when enabled.

Steps To Reproduce

 {
    "folke/noice.nvim",
    event = "VeryLazy",
    opts = {
      routes = {}, -- when the user defines custom routes, the following presets no longer work
      presets = { long_message_to_split = true, cmdline_output_to_split = true },
    },
  },

Expected Behavior

I would expect the routes defined in long_message_to_split and cmdline_output_to_split to be appended to the routes entry in the user config setup table.

Repro

-- DO NOT change the paths and don't remove the colorscheme
local root = vim.fn.fnamemodify("./.repro", ":p")

-- set stdpaths to use .repro
for _, name in ipairs({ "config", "data", "state", "cache" }) do
  vim.env[("XDG_%s_HOME"):format(name:upper())] = root .. "/" .. name
end

-- bootstrap lazy
local lazypath = root .. "/plugins/lazy.nvim"
if not vim.loop.fs_stat(lazypath) then
  vim.fn.system({ "git", "clone", "--filter=blob:none", "https://github.com/folke/lazy.nvim.git", lazypath, })
end
vim.opt.runtimepath:prepend(lazypath)

-- install plugins
local plugins = {
  "folke/tokyonight.nvim",
  "folke/noice.nvim",
  -- add any other plugins here
}
require("lazy").setup(plugins, {
  root = root .. "/plugins",
})

vim.cmd.colorscheme("tokyonight")
-- add anything else here