RFR: 8287202: GHA: Add macOS aarch64 to the list of default platforms for workflow_dispatch event

[Christoph Langer]

It seems that it was forgotten to add the macOS aarch64 platform to the default platforms of workflow_dispatch. Let's fix this.

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Commit messages:
 - JDK-8287202

Changes: https://git.openjdk.java.net/jdk/pull/8861/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8861&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8287202
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8861.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8861/head:pull/8861

PR: https://git.openjdk.java.net/jdk/pull/8861