[iOS] Resizing issue for animating streams

Summary
When animating the size & position of a stream, the size change doesn't respect the animation. It just becomes the end size immediately. It happens to both local and remote streams. We don't see the same issue on Android, iOS only.

Steps to reproduce the behavior:
1. Have a container view to hosting the stream as its subview (probably set the background color of the container a different color than the screen)
2. Use either manual layout or auto layout for the stream view
3. Animate size change of the container view
4. When making it bigger, the stream immediately becomes the end size and it can see it not animate along with the container. It's just like the container is becoming bigger and revealing the stream. When making it smaller, same thing happens. Now, the stream becomes small immediately and the container is shrinking.

Expected
The stream should be animated along with the container.

Video
https://user-images.githubusercontent.com/5403473/115479005-49633100-a1fc-11eb-8a3f-3f5fd7fd7f2f.mov
[You can scrub the video by looking at it frame by frame]

Configuration
- Version of the release: beta 9
- iOS: 14+
- Device: iPhone 11 Pro

Additional context
Not a hard blocker on video calling experience, but it really makes our UX not delightful and we should address it soon.