Upgrade 1 arm64 and x86 macOS 14 devicelab bot in staging pool to iOS 18

[vashworth]

Type of Request

infra task

Infrastructure Environment

Devicelab

What is happening?

Prerequisites

• iOS 18 has been released
• Run all flutter/flutter macOS tests using Xcode 16 and iOS 18 simulator #148899
• Upgrade 50% of devicelab bots in each pool to macOS 14.5 #148881

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• Upgrade 1 x86 macOS 14 staging devicelab bot to iOS 18
• Upgrade 1 arm64 macOS 14 staging devicelab bot to iOS 18

When ready to upgrade, file an issue with a list of explicit bots listed by name to upgrade and include the following additional instructions:

1. Before starting upgrade, quarantine the bot
2. After upgrading device
   1. Open Xcode 16 from /opt/flutter/xcode/[insert Xcode build version]/XCode.app
   2. In the top bar, open Window > Device and Simulators
   3. The window that opens should show the connected device
   4. Accept the Trust dialog on the iPhone device
   5. If you get the dialog on the device twice, you may need to accept it once, disconnect, reconnect, and accept again.
   6. Wait for the yellow bar at the top of the Device and Simulators window to go away - It should take a minute or so to Copy cache symbols
3. Unquarantine the bot

See #142326 as example.

Steps to reproduce

No response

Expected results

No response