[jdk21u-dev] RFR: 8325194: GHA: Add macOS M1 testing [v3]

[George Adams]

> Now that macOS M1 executors are [available in GitHub actions](https://github.blog/changelog/2024-01-30-github-actions-introducing-the-new-m1-macos-runner-available-to-open-source/) it makes sense to move the build to run on M1 (rather than cross-compiled) and also enable testing on the platform.

George Adams has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  Backport 3c91b59ef9c992718d73f2fc9fa50ad2ead78208

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Changes:
  - all: https://git.openjdk.org/jdk21u-dev/pull/238/files
  - new: https://git.openjdk.org/jdk21u-dev/pull/238/files/2a8f9d3d..5f7d28e5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=238&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=238&range=01-02

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/238.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/238/head:pull/238

PR: https://git.openjdk.org/jdk21u-dev/pull/238