coverage: Add #[rustfmt::skip] to tests with non-standard formatting

These tests deliberately use non-standard formatting, so that the line
execution counts reported by `llvm-cov` reveal additional information about
where code regions begin and end.

tests/coverage/lazy_boolean.rs

@@ -1,5 +1,6 @@
 #![allow(unused_assignments, unused_variables)]
 
+#[rustfmt::skip]
 fn main() {
     // Initialize test constants in a way that cannot be determined at compile time, to ensure
     // rustc and LLVM cannot optimize out statements (or coverage counters) downstream from