Allow platform admin to change instance types when billing expired

### Description

**As a** FlowFuse Admin
**I want to** be able to change an instance type when billing has expired
**so that** I can facilitate team type downgrades

e.g. Team with 2 instances (1 small + 1 medium) wants to transition to a team type that only allows small instance types.

Currently even Admin users are redirected to the billing page when trying to change an instance type (for a susspened instance)

### Which customers would this be available to

None

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate