RFR: 8329998: Remove double initialization for parts of small TypeArrays in ZObjArrayAllocator

[Stefan Karlsson]

On Wed, 10 Apr 2024 13:06:47 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

> [JDK-8139457](https://bugs.openjdk.org/browse/JDK-8139457) introduced non-word aligned payloads for TypeArrays. This required adaptation in `ZObjArrayAllocator` segmented array allocator. But the implementation does this adaptation even when the size is small enough and dispatches the allocation to `ObjArrayAllocator`, which already handles clearing this memory.
> 
> Instead move the initialization of any unaligned payload start to after the segmented allocation decision.

Marked as reviewed by stefank (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/18721#pullrequestreview-1991679752