Switching over from iOS-15 to iOS-16 in .ci.yaml. (flutter#118807) (flutter#118963)

This will run tests on new iphone11 devicelab devices
which are running iOS-16.

Bug:flutter#117237

Co-authored-by: yusuf-goog <[email protected]>

Author: XilaiZhang

.ci.yaml

@@ -131,8 +131,8 @@ platform_properties:
         ]
       os: Mac-12
       cpu: x86
-      device_os: iOS-15
-      xcode: 14a5294e
+      device_os: iOS-16
+      xcode: 14c18 # Xcode 14.2 to support iOS 16.2 in devicelab.
   mac_arm64_ios:
     properties:
       dependencies: >-
@@ -143,8 +143,8 @@ platform_properties:
         ]
       os: Mac-12
       cpu: arm64
-      device_os: iOS-15
-      xcode: 14a5294e
+      device_os: iOS-16
+      xcode: 14c18 # Xcode 14.2 to support iOS 16.2 in devicelab.
   windows:
     properties:
       dependencies: >-