RFR: 8295714: GHA ::set-output is deprecated and will be removed

Thu Oct 20 10:07:40 UTC 2022

We need to transition to use the new `$GITHUB_OUTPUT` method instead. 

This needs to be fixed since it is currently spamming the summary with warnings, and will stop working soon.

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Commit messages:
 - 8295714: GHA ::set-output is deprecated and will be removed

Changes: https://git.openjdk.org/jdk/pull/10785/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10785&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295714
  Stats: 28 lines in 11 files changed: 1 ins; 0 del; 27 mod
  Patch: https://git.openjdk.org/jdk/pull/10785.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10785/head:pull/10785

PR: https://git.openjdk.org/jdk/pull/10785