RFR: 8365991: AArch64: Ignore BlockZeroingLowLimit when UseBlockZeroing is false [v2]

[Patrick Zhang]

On Thu, 4 Sep 2025 09:37:21 GMT, Andrew Haley <aph at openjdk.org> wrote:

> OK, but please edit the claims at the top of this PR to respect the new reality. In particular, please state the test cases which are improved.

Updated. 
Had a new change (https://github.com/openjdk/jdk/pull/26917/commits/f23abb9439398fa571da3c3b4ae17573c7f8ddd9) to set `BlockZeroingLowLimit` to **256** if `is_zva_enabled()` returns false, otherwise we would have 0 from `_zva_length`.

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PR Comment: https://git.openjdk.org/jdk/pull/26917#issuecomment-3257382267