[jdk11u-dev] RFR: 8268185: Update GitHub Actions for jtreg 6 [v3]

[George Adams]

> simple backport of [JDK-8268185](https://bugs.openjdk.java.net/browse/JDK-8268185): Update GitHub Actions for jtreg 6 in preparation for the GitHub action rewrite backport

George Adams has refreshed the contents of this pull request, and previous commits have been removed. Incremental views are not available. The pull request now contains one commit:

  Backport e27c4d463d920994b79b8163f063ad74f6ee5d59

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Changes:
  - all: https://git.openjdk.org/jdk11u-dev/pull/1239/files
  - new: https://git.openjdk.org/jdk11u-dev/pull/1239/files/90a9c2ff..b3bd517c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1239&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1239&range=01-02

  Stats: 19 lines in 9 files changed: 1 ins; 0 del; 18 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1239.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1239/head:pull/1239

PR: https://git.openjdk.org/jdk11u-dev/pull/1239