chore: delete import that was missed in #18274

Author: mmalerba

src/cdk/testing/testbed/proxy-zone-types.d.ts

@@ -16,8 +16,6 @@
  * be pulled in from the original type definitions.
  */
 
-import {HasTaskState, Zone, ZoneDelegate} from './zone-types';
-
 export interface ProxyZoneStatic {
   assertPresent: () => ProxyZone;
   get(): ProxyZone;