Types preview: remove private DT route types

We continue to maintain support for these import locations in the types
on DefinitelyTyped, but remove them here so that users trying the
preview types do not accidentally depend on them.

type-tests/preview/@ember/routing-test/route.ts

@@ -5,8 +5,7 @@ import type Array from '@ember/array';
 import EmberObject from '@ember/object';
 import Controller from '@ember/controller';
 import type Transition from '@ember/routing/transition';
-import type { RouteInfoWithAttributes } from '@ember/routing/route-info';
-import type RouteInfo from '@ember/routing/route-info';
+import { expectTypeOf } from 'expect-type';
 
 class Post extends EmberObject {}
 
@@ -207,25 +206,3 @@ class WithImplicitParams extends Route {
 
 type ImplicitParams = WithImplicitParams extends Route<any, infer T> ? T : never;
 expectTypeOf<ImplicitParams>().toEqualTypeOf<RouteParams>();
-
-// back-compat for existing users of these
-// NOTE: we will *not* migrate the private import locations when moving to
-// publish from Ember itself.
-import type PrivateTransition from '@ember/routing/-private/transition';
-declare let publicTransition: Transition;
-declare let oldPrivateTransition: PrivateTransition;
-publicTransition = oldPrivateTransition;
-oldPrivateTransition = publicTransition;
-
-import type PrivateRouteInfo from '@ember/routing/-private/route-info';
-declare let publicRouteInfo: RouteInfo;
-declare let privateRouteInfo: PrivateRouteInfo;
-publicRouteInfo = privateRouteInfo;
-privateRouteInfo = publicRouteInfo;
-
-import type PrivateRouteInfoWithAttributes from '@ember/routing/-private/route-info-with-attributes';
-import { expectTypeOf } from 'expect-type';
-declare let publicRouteInfoWithAttributes: RouteInfoWithAttributes;
-declare let privateRouteInfoWithAttributes: PrivateRouteInfoWithAttributes;
-publicRouteInfoWithAttributes = privateRouteInfoWithAttributes;
-privateRouteInfoWithAttributes = publicRouteInfoWithAttributes;