[jdk26u] RFR: 8373913: Refactor serialization tests to use JUnit

[Shivangi Gupta]

Straight Backport.All tests passed

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Commit messages:
 - Backport 3007365b73d400ee6a5ea9a9041899bb81cf357a

Changes: https://git.openjdk.org/jdk26u/pull/77/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk26u&pr=77&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373913
  Stats: 443 lines in 14 files changed: 89 ins; 87 del; 267 mod
  Patch: https://git.openjdk.org/jdk26u/pull/77.diff
  Fetch: git fetch https://git.openjdk.org/jdk26u.git pull/77/head:pull/77

PR: https://git.openjdk.org/jdk26u/pull/77