Switch to exhaustive groups with small B coefficient

src/modules/recovery/tests_exhaustive_impl.h

@@ -43,8 +43,7 @@ void test_exhaustive_recovery_sign(const secp256k1_context *ctx, const secp256k1
                       (k * (EXHAUSTIVE_TEST_ORDER - s)) % EXHAUSTIVE_TEST_ORDER == (i + r * j) % EXHAUSTIVE_TEST_ORDER);
                 /* The recid's second bit is for conveying overflow (R.x value >= group order).
                  * In the actual secp256k1 this is an astronomically unlikely event, but in the
-                 * small group used here, it will be the case for all points except the ones where
-                 * R.x=1 (which the group is specifically selected to have).
+                 * small group used here, it will almost certainly be the case for all points.
                  * Note that this isn't actually useful; full recovery would need to convey
                  * floor(R.x / group_order), but only one bit is used as that is sufficient
                  * in the real group. */