core: drop legacy validator (#497)

packages/hydrooj/src/interface.ts

@@ -733,7 +733,6 @@ export interface Lib extends Record<string, any> {
     rank: typeof import('./lib/rank');
     rating: typeof import('./lib/rating');
     testdataConfig: typeof import('./lib/testdataConfig');
-    validator: typeof import('./lib/validator');
     template?: any;
     problemSearch: ProblemSearch;
 }