[jdk21u-dev] RFR: 8296787: Unify debug printing format of X.509 cert serial numbers

[Goetz Lindenmaier]

I backport this for parity with 21.0.6-oracle.

Trivial resolve in Debug.java, probably recognized clean.

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Commit messages:
 - Backport c328f9589ddc3a981a2c63801bd991f8e593e69f

Changes: https://git.openjdk.org/jdk21u-dev/pull/966/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=966&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8296787
  Stats: 65 lines in 18 files changed: 19 ins; 3 del; 43 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/966.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/966/head:pull/966

PR: https://git.openjdk.org/jdk21u-dev/pull/966