Move iOS CI runners off macos-14 image

[freakboy3742]

Feature or enhancement

Proposal:

#145098 updated the GitHub Actions configurations to use macos-26 images for macOS jobs. Updating iOS to use macos-26 was deferred at the time because of issues with the stability of iOS on GitHub Actions (actions/runner-images#12777). iOS jobs remain on macos-14.

However, deprecation of the macos-14 runner has begun (actions/runner-images#13518), with the image being unsupported by November 2 2026. We need to move off the macos-14 image by then.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

• CI: move Apple Silicon macOS workflows to macos-26 (Tahoe) #145098 - macOS-26 upgrade
• iOS test simulators fail to start on 20250811 macOS-15 build actions/runner-images#12777 - blocker on upgrading
• [macOS] The macOS 14 Sonoma based runner images will begin deprecation on July 6th and will be fully unsupported by November 2nd for GitHub Actions and Azure DevOps actions/runner-images#13518 - Deprecation schedule for macos-14 image

Linked PRs

• gh-153631: Move to macos-26 runner for iOS #153632
• [3.15] gh-153631: Move to macos-26 runner for iOS (GH-153632) #153673
• [3.14] gh-153631: Move to macos-26 runner for iOS (GH-153632) #153674
• [3.13] gh-153631: Ensure iOS simulator is running before starting build (GH-153632) #153675