[jdk17u-dev] RFR: 8273040: Turning off JpAllowDowngrades (or Upgrades)

[Goetz Lindenmaier]

I backport this for parity with 17.0.5-oracle.

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Commit messages:
 - Backport 22a7191f700c6966c59dcd12476f01452243542b

Changes: https://git.openjdk.org/jdk17u-dev/pull/550/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=550&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8273040
  Stats: 17 lines in 3 files changed: 7 ins; 5 del; 5 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/550.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev pull/550/head:pull/550

PR: https://git.openjdk.org/jdk17u-dev/pull/550