RFR: 8369483: Cleanup dead code in HandleArea

[Francesco Andreuzzi]

On Thu, 9 Oct 2025 08:06:35 GMT, Joel Sikström <jsikstro at openjdk.org> wrote:

> Hello,
> 
> When reading up on how HandleArea and HandleMark's work, I found some dead code and comments in the HandleArea class. This makes the code a bit easier to read and understand.
> 
> Testing:
> * Oracle's tier1-2

Marked as reviewed by fandreuzzi (Author).

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PR Review: https://git.openjdk.org/jdk/pull/27717#pullrequestreview-3317903477