Fix iOS packaging pipeline (#26426)

### Description
<!-- Describe your changes. -->

Change Xcode version from 16.4 to 16.2, according to what's available on
the build agent image.

Adjust casing in `xcodebuild -destination` argument.

### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->

Fix iOS packaging pipeline issues.

Author: edgchen1

tools/ci_build/github/apple/test_apple_packages.py

@@ -206,7 +206,7 @@ def _test_apple_packages(args):
                         "-scheme",
                         "macos_package_test",
                         "-destination",
-                        "platform=macos",
+                        "platform=macOS",
                     ],
                     shell=False,
                     check=True,

tools/ci_build/github/azure-pipelines/templates/stages/mac-ios-packaging-build-stage.yml

@@ -17,8 +17,8 @@ stages:
       # Note: Keep the Xcode version and iOS simulator version compatible.
       # Check the table here to see what iOS simulator versions are supported by a particular Xcode version:
       # https://developer.apple.com/support/xcode/
-      xcodeVersion: "16.4"
-      iosSimulatorRuntimeVersion: "18.5"
+      xcodeVersion: "16.2"
+      iosSimulatorRuntimeVersion: "18.2"
       buildSettingsFile: "tools/ci_build/github/apple/default_full_apple_framework_build_settings.json"
       cPodName: onnxruntime-c
       objcPodName: onnxruntime-objc