[jdk11u-dev] RFR: 8318039: GHA: Bump macOS and Xcode versions

[Antonio Vieiro]

The `macos-11`  github runners [were deprecated and removed in June 2024](https://github.blog/changelog/2024-05-20-actions-upcoming-changes-to-github-hosted-macos-runners/) , making the `macos` tests to hang in `openjdk11u-dev` (and other OpenJDK repositories).

[JDK-8335793 GHA: Bump macOS and Xcode versions](https://bugs.openjdk.org/browse/JDK-8335793) upgraded the version [from `macos-11` to `macos-13`](https://github.com/openjdk/jdk11u-dev/pull/2835).  This upgrade in github runners required a long list of changes in `openjdk11u-dev` that proved difficult to review.

In order to ease the review process this PR downgrades the version of github runners in `jdk11u-dev` from the current `macos-13` to `macos-12` and `xcode-13.4.1`. This will require a single backport of [JDK-8299254 Support dealing with standard assert macro](https://bugs.openjdk.org/browse/JDK-8299254) (a follow-up to this PR), making the review process easier.

Once the github actions are running again in `macos-12` an upgrade to `macos-13` could be performed, if required, with some more additional PRs.

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Commit messages:
 - Backport 7144027dff495b623428bd9cd891c0ed912035a4

Changes: https://git.openjdk.org/jdk11u-dev/pull/2936/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2936&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318039
  Stats: 5 lines in 3 files changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2936.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2936/head:pull/2936

PR: https://git.openjdk.org/jdk11u-dev/pull/2936