Fix proptest for tx status manager (#2893)

## Description
This PR adjusts the logic in the proptest to properly decide whether the
status should be expected as already pruned or not.

Failure spotted here:
https://github.com/FuelLabs/fuel-core/actions/runs/13974630753/job/39125181263?pr=2892

### Before requesting review
- [X] I have reviewed the code myself