[FEATURE]: delete old guest users from DB

[CatiaAntunes96]

Summary

To address the issue of guest users that are no longer active in the database, we need to implement a mechanism to automatically delete accounts that have been inactive for a certain period of time (exact time interval to be determined). This can be achieved by setting up a cron job in the backend that regularly checks for inactive accounts and removes them.

User story it relates to

#674