Remove long term unverified accounts

### Epic

#393

### Description

**As a:** admin

**I want to:** have accounts which have remained at unverified for a significant (TBC) period be removed from the system

**So that:** those email addresses can signup for a fresh account, and my database is kept tidy

### Which customers would this be availble to

- [X] All Users, (CE)
- [ ] Specific Project Types (EE)
- [ ] Specific Team Tiers (EE)
- [ ] Other (See comments)

### Acceptance Criteria

_No response_