Revert "[iOS] NavigationPage: Fix large-title collapse for wrapped scroll content (#36511)" (#37810)

## Description

This reverts #36511. The `Issue33037NonShell` UI tests added by that PR
are unstable on iOS 26.5, while the proxy-based implementation is being
reconsidered in #37548. Reverting avoids shipping the current
implementation while that work continues.

## Why revert

- Five scenarios fail in grouped iOS 26.5 runs despite passing
individually and on iOS 26.3:
  - `Issue33037FixedHeaderCollectionViewButton`
  - `Issue33037ShortFixedHeaderCollectionViewButton`
  - `Issue33037GridScrollViewButton`
  - `ProgrammaticScrollCollapsesLargeTitle`
  - `ProgrammaticWebViewScrollCollapsesLargeTitle`
- Restarting the app before each test makes all five pass, showing that
the failures are specific to shared test-session state and do not
reproduce when the scenarios run independently.
- `Issue33037NonShell_GridScrollView_BeforeScroll` also produces an
unstable first-paint visual difference.
- #37548 is investigating a replacement for the proxy mechanism and
remains in progress.

## Changes

- Restores `NavigationRenderer.cs` to its pre-#36511 behavior.
- Removes the `Issue33037NonShell` HostApp scenarios and UI tests.
- Removes the nine associated iOS 26 snapshot baselines.

Author: HarishwaranVijayakumar