Revert "test(animations): ensure :enter callbacks fire on container insertion (#19674)"

This reverts commit 41f57affb6.
As it was synched together with 5a9ed2de27
which broke an internal test.

packages/core/test/animation/animation_integration_spec.ts

@@ -340,42 +340,6 @@ export function main() {
            expect(completed).toBe(true);
          }));
 
-      it('should always fire inner callbacks even if no animation is fired when a view is inserted',
-         fakeAsync(() => {
-           @Component({
-             selector: 'if-cmp',
-             template: `
-          <div *ngIf="exp">
-            <div @myAnimation (@myAnimation.start)="track($event)" (@myAnimation.done)="track($event)"></div>
-          </div>
-        `,
-             animations: [
-               trigger('myAnimation', []),
-             ]
-           })
-           class Cmp {
-             exp: any = false;
-             log: string[] = [];
-             track(event: any) { this.log.push(`${event.triggerName}-${event.phaseName}`); }
-           }
-
-           TestBed.configureTestingModule({declarations: [Cmp]});
-
-           const engine = TestBed.get(ɵAnimationEngine);
-           const fixture = TestBed.createComponent(Cmp);
-           const cmp = fixture.componentInstance;
-           fixture.detectChanges();
-           flushMicrotasks();
-
-           expect(cmp.log).toEqual([]);
-
-           cmp.exp = true;
-           fixture.detectChanges();
-           flushMicrotasks();
-
-           expect(cmp.log).toEqual(['myAnimation-start', 'myAnimation-done']);
-         }));
-
       it('should only turn a view removal as into `void` state transition', () => {
         @Component({
           selector: 'if-cmp',