This fixes a variety of testsuite failures with integer-simple of the form

```
--- typecheck/should_fail/tcfail072.run/tcfail072.stderr.normalised
+++ typecheck/should_fail/tcfail072.run/tcfail072.comp.stderr.normalised
@@ -12,7 +12,7 @@
           -- Defined in ‘integer-<IMPL>-<VERSION>:GHC.Integer.Type’
         instance Ord () -- Defined in ‘GHC.Classes’
         ...plus 21 others
-        ...plus three instances involving out-of-scope types
+        ...plus two instances involving out-of-scope types
         (use -fprint-potential-instances to see them all)
      In the expression: g A
       In an equation for ‘g’: g (B _ _) = g A
```

In service of fixing #16043.