fix(data): remove strict typing for optimistic false (#3020)

Additional overload for `.add()` on NgRx Data Service causes issue when passing in `boolean` to `isOptimistic`. Remove overload as it should not be needed. Resolves #2928

Author: yharaskrik

modules/data/src/entity-services/entity-collection-service-base.ts

@@ -145,10 +145,6 @@ export class EntityCollectionServiceBase<
     entity: Partial<T>,
     options: EntityActionOptions & { isOptimistic: false }
   ): Observable<T>;
-  add(
-    entity: T,
-    options?: EntityActionOptions & { isOptimistic?: true }
-  ): Observable<T>;
   add(entity: T, options?: EntityActionOptions): Observable<T> {
     return this.dispatcher.add(entity, options);
   }