test(turbopack): strongly read test operations (#98247)
## Summary
Replace top-level consistency suppression in straightforward backend
tests with local operation roots that are read strongly consistently.
Inner operation functions keep each migration scoped to its test.
## Verification
- `cargo test -p turbo-tasks-backend --test filter_unused_args --test
panics --test task_statistics`
- `cargo fmt --all -- --check`
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Co-authored-by: vercel-fleet-prod[bot] <318278635+vercel-fleet-prod[bot]@users.noreply.github.com>
Co-authored-by: Luke Sandberg <210140+lukesandberg@users.noreply.github.com>
