This is a step towards being able to unify the two coverage test directories.
There are two tests that require adjustment:
- `overflow.rs` requires an explicit `-Coverflow-checks=yes`
- `sort_groups.rs` is sensitive to provably unused instantiations
These changes were made by manually running `rustfmt` on all of the test files,
and then manually undoing all cases where the original formatting appeared to
have been deliberate.
`rustfmt +nightly --config-path=/dev/null --edition=2021 tests/run-coverage*/**/*.rs`
