backport: fix(luarc.json): increase workspace.preloadFileSize (#39716)

Problem:
When using the default `lua_ls` config from nvim-lspconfig, the following info message gets printed:

```
LSP[lua_ls] Too large file: src/nvim/eval.lua skipped. The currently set size limit is: 500 KB, and the file size is: 511.133 KB.
```

Solution:
Set `workspace.preloadFileSize` to 1000 KB instead of the default 500 KB.

(cherry picked from commit 5d1910e1e0)

Co-authored-by: Olivia Kinnear <git@superatomic.dev>

.luarc.json

@@ -9,6 +9,7 @@
       "build",
       "test"
     ],
+    "preloadFileSize": 1000,
     "checkThirdParty": "Disable"
   },
   "diagnostics": {