Session Replay: consolidate window size detection onto OnLayoutChangeListener

## Summary

`WindowRecorder.determineWindowSize` currently has two detection paths for window size changes:

1. **Synchronous**: if the root already has size at registration time, compare and emit immediately.
2. **Deferred** (`OnPreDrawListener`): if the root has no size yet (typical — Curtains fires `onRootViewsChanged` before the first traversal), register a listener that re-checks on every pre-draw and removes itself once size is known.

[#5333](https://github.com/getsentry/sentry-java/pull/5333) added a third path — an `OnLayoutChangeListener` per tracked root — to detect same-root resizes for activities with `configChanges` (Unity, video players). This listener strictly subsumes the `OnPreDrawListener` path: it fires on the first `View.layout(0, 0, W, H)` (bounds differ from the initial 0/0/0/0), which happens on the same Choreographer frame but before draw.

## Proposed change

Replace the `OnPreDrawListener` path with the `OnLayoutChangeListener`, keeping the synchronous check for the rare case where the root already has size at add time. This would:

- Remove the dual-listener setup (simpler code, one mechanism instead of two).
- Eliminate the per-preDraw iteration that checks `hasSize()` and `root == currentRoot` on every draw until size is known.
- Unify initial detection and subsequent resize detection into a single listener.

The `OnLayoutChangeListener` already has the latest-root guard (`v != rootViews.lastOrNull()?.get()` → skip), matching the `OnPreDrawListener`'s existing `root != currentRoot` guard.

## Why it wasn't done in #5333

The refactor changes behavior for all apps, not just `configChanges` activities. It was kept out of scope to limit regression risk in the SurfaceView capture PR.