[jdk21u-dev] RFR: 8308453: Convert JKS test keystores in test/jdk/javax/net/ssl/etc to PKCS12

[Goetz Lindenmaier]

I backport this for parity with 21.0.4-oracle.

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Commit messages:
 - Backport 1696603ccd43a279efa35d9f6617ce664bfdf504

Changes: https://git.openjdk.org/jdk21u-dev/pull/445/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=445&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308453
  Stats: 101 lines in 23 files changed: 7 ins; 33 del; 61 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/445.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/445/head:pull/445

PR: https://git.openjdk.org/jdk21u-dev/pull/445