RFR: 8343923: GHA: Switch to Xcode 15 on MacOS AArch64 runners

[Aleksey Shipilev]

We use macos-14 images for macos-aarch64 runners. We use Xcode 14.3.1 there. Xcode 14 goes away from those runners, as per: https://github.com/actions/runner-images/issues/10703. Current GH runner docs say macos-14 image defaults to Xcode 15.4: https://github.com/actions/runner-images/blob/main/images/macos/macos-14-Readme.md. We can switch to that.

I think this policy change is why we started seeing GHA failures like:


Run # On macOS we need to install some dependencies for testing
==> Summary
🍺 /opt/homebrew/Cellar/make/4.4.1: 17 files, 1.3MB
xcode-select: error: invalid developer directory '/Applications/Xcode_14.3.1.app/Contents/Developer'
Error: Process completed with exit code 1.

-------------

Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/22005/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22005&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343923
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/22005.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22005/head:pull/22005

PR: https://git.openjdk.org/jdk/pull/22005