Make this test slightly less fragile; NFC

The rule IDs are not stable, so this uses a regex for the rule ids
instead of concrete values. It also moves the CHECK lines below the
code so that it's easier to modify the test in the future. It also
breaks the CHECK lines into multiple lines to improve the performance
of the test and aid in debugging failures. Finally, it adds a comment
to the top of the test explaining that things are still rather fragile.