[SE-3409] Process for handling stuck tickets

This ticket creates a process for handling stuck tickets. It adds advice to the Epic management guide.

JIRA tickets: https://tasks.opencraft.com/browse/SE-3409

Discussions: https://forum.opencraft.com/t/how-to-handle-tickets-that-jeopardize-an-epic/817/3

Dependencies: None

Reviewers

• @bradenm
• @mavidser