[jdk21u-dev] RFR: 8342183: Update tests to use stronger algorithms and keys

[Goetz Lindenmaier]

I backport this for parity with 21.0.6-oracle.

Resolved Copyright of SignedOrder, probably clean.

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Commit messages:
 - Backport c82ad845e101bf5d97c0744377d68002907d4a0e

Changes: https://git.openjdk.org/jdk21u-dev/pull/1146/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1146&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342183
  Stats: 267 lines in 35 files changed: 142 ins; 8 del; 117 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1146.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1146/head:pull/1146

PR: https://git.openjdk.org/jdk21u-dev/pull/1146