schemastore not loaded jsonls/yamlls

### Checklist

- [x] I have searched through the AstroNvim documentation
- [x] I have searched through the existing issues of this project
- [x] I have searched the existing issues of plugins related to this issue
- [x] I can replicate the bug with the minimal `repro.lua` provided below

### Neovim version (nvim -v)

v0.12.2 RelWithDebInfo

### Operating system/version

ArchLinux

### Terminal/GUI

ghostty

### Describe the bug

In the `vim.lsp.config` the `on_new_config` is still not supported. Issue ref - https://github.com/neovim/neovim/issues/32287

So whenever I open the package.json, pnpm-workspace.yaml file I get no auto-completion by default.

### Steps to Reproduce

1. clone the AstroNvim starter
2. Add the following in `community.lua`
```lua
---@type LazySpec
return {
"AstroNvim/astrocommunity",
{ import = "astrocommunity.pack.json" },
{ import = "astrocommunity.pack.yaml" },
}
```
3. Open package.json or pnpm-workspace.yaml file, no auto-completion is observed

### Expected behavior

Auto-completion should be working.

Please use `before_init` instead of on_new_config(same as lazyvim)
```lua
before_init = function(_, config)
--- ...
end
```

### Screenshots

_No response_

### Additional Context

_No response_

### Minimal configuration

```Lua
-- save as repro.lua
-- run with nvim -u repro.lua
-- DO NOT change the paths
local root = vim.fn.fnamemodify("./.repro", ":p")

-- set stdpaths to use .repro
for _, name in ipairs({ "config", "data", "state", "runtime", "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
-- stylua: ignore
vim.fn.system({ "git", "clone", "--filter=blob:none", "https://github.com/folke/lazy.nvim.git", "--branch=stable", lazypath })
end
vim.opt.rtp:prepend(vim.env.LAZY or lazypath)

-- install plugins
local plugins = {
{ "AstroNvim/AstroNvim", import = "astronvim.plugins" },
{ "AstroNvim/astrocommunity", { import = "astrocommunity.pack.json" }, { import = "astrocommunity.pack.yaml" } },

-- add any other plugins/customizations here
}
require("lazy").setup(plugins, {
root = root .. "/plugins",
})

-- add anything else here (autocommands, vim.filetype, etc.)
```

Inspect the imported astrocommunity.pack.json and astrocommunity.pack.yaml plugin specifications and the LSP configuration they use; compare the current on_new_config path with the requested before_init hook. Reproduce with repro.lua by opening package.json and pnpm-workspace.yaml, then confirm schemastore completion appears.

Written by the indexing model from the issue text.