ci: fix iOS builds (#1479)

## 📜 Description

Fixing CI failures for iOS e2e jobs (building iOS 26 app).

## 💡 Motivation and Context

XCode 26.1 can not build app anymore:
https://github.com/kirillzyusko/react-native-keyboard-controller/actions/runs/26761419312/job/78889726965

So in this PR I'm switching to the same version as I have on my PC
(26.4). We can not switch iOS simulator to iOS 26.4 because we need to
re-generate assets in this case, so for now we only update build
machine.

## 📢 Changelog

<!-- High level overview of important changes -->
<!-- For example: fixed status bar manipulation; added new types
declarations; -->
<!-- If your changes don't affect one of platform/language below - then
remove this platform/language -->

### CI

- use Xcode 26.4 for building tests for iOS 26;

## 🤔 How Has This Been Tested?

Tested manually via this PR.

## 📸 Screenshots (if appropriate):

<img width="777" height="296" alt="image"
src="https://github.com/user-attachments/assets/5d098ea9-2a8f-4d97-b414-b41d0364b91b"
/>

## 📝 Checklist

- [x] CI successfully passed
- [x] I added new mocks and corresponding unit-tests if library API was
changed