GTRIA-1256 - fix export attendees via email functionality

[masoodahmed]

🎫 Ticket

GTRIA-1256

🗒️ Description

Updated the logic to check if the email with attendees needs to be sent. Also, updated the conditional to check if status is empty to avoid false success or failure message.

🎥 Artifacts

N/A

✔️ Checklist

• [X] Changelog entry in the readme.txt file.
• [ ] Code is covered by NEW wpunit or integration tests.
• [ ] Code is covered by EXISTING wpunit or integration tests.
• [ ] Are all the required tests passing?
• [ ] Automated code review comments are addressed.
• [ ] Have you added Artifacts?
• [X] Check the base branch for your PR.
• [ ] Add your PR to the project board for the release.