src: fix empty string access in dotenv
The value string added in (https://github.com/nodejs/node/pull/51289) can sometimes be empty. We check for it before accessing it.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
The value string added in (https://github.com/nodejs/node/pull/51289) can sometimes be empty. We check for it before accessing it.