fix(config): remove deprecated field

[richardkeit]

• Running the installer process, this field is no longer required

| 1732510628170 | $ /landing-zone-accelerator-on-aws/source/packages/@aws-accelerator/tools/node_modules/.bin/ts-node --transpile-only uninstaller.ts --installer-stack-name AWSAccelerator-InstallerStack --ignore-termination-protection true --full-destroy true --partition --debug --delete-data --ignore-termination-protection --delete-bootstraps true --delete-pipelines                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| 1732510628170 | (node:26906) [DEP0128] DeprecationWarning: Invalid 'main' field in '/landing-zone-accelerator-on-aws/source/node_modules/@aws-accelerator/config/package.json' of 'dist/index.js'. Please either fix that or report it to the module author                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |

• Silent error (without debug option) is hard to diagnose (given default behaviour in Cloudformation template from the workshop doesn't expose the entry point)