feat(serverless): add basic sandbox isolation and flexible driver options (#17176)

## Overview
- Add a DISABLED serverless driver to explicitly turn off execution
- Clarify self-hosting docs with driver options and recommended usage
- Keep integration coverage for serverless function execution (default +
external package example)

## Notes
- Local driver remains the default for development usage; Lambda or
Disabled recommended for production deployments
- No functional changes to Lambda execution

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Introduces flexible serverless execution modes and safer local
execution.
> 
> - **New driver:** `DISABLED` serverless driver with wiring in
`serverless.interface`, factory, module provider, and GraphQL exception
mapping; new exception code `SERVERLESS_FUNCTION_DISABLED`.
> - **Local driver hardening:** Strip `NODE_OPTIONS` when spawning child
processes; cleanup promise signature; better log capture.
> - **Dependency build reliability:** Use `execFile` with bundled Yarn
(`.yarn/releases/yarn-4.9.2.cjs`), strip `NODE_OPTIONS`, improved error
messages, and parallel cleanup excluding `node_modules`.
> - **Docs:** Add serverless section detailing `SERVERLESS_TYPE` options
(LOCAL, LAMBDA, DISABLED), security notice, and recommended configs.
> - **Config/env:** Default
`IS_WORKSPACE_CREATION_LIMITED_TO_SERVER_ADMINS` set to `true`
(examples/tests default `false`); sample envs updated.
> - **Tests:** Add integration tests and GraphQL helpers for creating,
updating, publishing, executing, and deleting serverless functions,
including external package usage and error paths.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
1a2958cc19cff1b0108c51b83095bbf95e75d931. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

packages/twenty-server/src/engine/core-modules/twenty-config/config-variables.ts

@@ -375,7 +375,7 @@ export class ConfigVariables {
     type: ConfigVariableType.BOOLEAN,
   })
   @IsOptional()
-  IS_WORKSPACE_CREATION_LIMITED_TO_SERVER_ADMINS = false;
+  IS_WORKSPACE_CREATION_LIMITED_TO_SERVER_ADMINS = true;
 
   @ConfigVariablesMetadata({
     group: ConfigVariablesGroup.STORAGE_CONFIG,