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

[Per Minborg]

On Wed, 30 Apr 2025 06:46:07 GMT, Volkan Yazici <vyazici at openjdk.org> wrote:

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

Looks fine! Thanks for this cleanup.

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Marked as reviewed by pminborg (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24959#pullrequestreview-2807429588