CI flake: `local_durability_crashes_on_new_segment_if_not_enough_space` did not panic

https://github.com/clockworklabs/SpacetimeDB/actions/runs/26968714237/job/79578902018
```
2026-06-04T18:08:25.4794371Z note: test did not panic as expected at crates/durability/tests/io/fallocate.rs:76:10
2026-06-04T18:08:25.4794554Z 
2026-06-04T18:08:25.4794615Z failures:
2026-06-04T18:08:25.4794832Z     io::fallocate::local_durability_crashes_on_new_segment_if_not_enough_space
```