RFR: 8355391: Use Long::hashCode in java.time

[Volkan Yazici]

Replace manual bitwise operations in `hashCode` implementations of `java.time` with `Long::hashCode`.

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Commit messages:
 - Use `Long::hashCode`

Changes: https://git.openjdk.org/jdk/pull/24959/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24959&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8355391
  Stats: 12 lines in 5 files changed: 0 ins; 5 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/24959.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24959/head:pull/24959

PR: https://git.openjdk.org/jdk/pull/24959