RFR: 8325659: Normalize Random usage by incubator vector tests

[Paul Sandoz]

On Mon, 8 Apr 2024 10:50:00 GMT, Evgeny Nikitin <enikitin at openjdk.org> wrote:

> Improve RNG usage in said tests:
> 
> 1. The RNG is not created by our Utils class, as suggested in our JTReg tests;
> 2. The seed, accordingly, is not a fixed value now, but truly random;
> 3. The tests that had been creating their own Random instances, are now using RAND static member from the AbstractVectorTest;
> 4. The generated tests sources have been re-generated.
> 
> The most important change is #2, it could add variability and help cover more JIT Compiler and Runtime scenarios.

Looks good, thank you for cleaning this up.

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Marked as reviewed by psandoz (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18675#pullrequestreview-1987442519