fix(zone.js): jest getRealSystemTime should return native time (#39127)

`jest.getRealSystemTime()` should return native `Date.now()`, the
current implemenation return the wrong value which is the fixed
number.

PR Close #39127

Author: JiaLiPassion

Diff for: packages/zone.js/lib/jest/jest.ts

@@ -200,7 +200,7 @@ Zone.__load_patch('jest', (context: any, Zone: ZoneType, api: _ZonePrivate) => {
       return function(self: any, args: any[]) {
         const fakeAsyncZoneSpec = Zone.current.get('FakeAsyncTestZoneSpec');
         if (fakeAsyncZoneSpec && isPatchingFakeTimer()) {
-          return fakeAsyncZoneSpec.getCurrentRealTime(args[0]);
+          return fakeAsyncZoneSpec.getRealSystemTime();
         } else {
           return delegate.apply(self, args);
         }