RFR: 8357913: Add `@Stable` to BigInteger and BigDecimal [v3]

[Per Minborg]

On Fri, 30 May 2025 22:07:06 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> Some static final arrays of BigInteger and BigDecimal are stable and immutable. We should add `@Stable` to give the optimizer more information
>
> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   BigInteger::mag remove Stable

The newly marked arrays are indeed only updated once. Can we see any benchmark showing a performance gain?

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PR Comment: https://git.openjdk.org/jdk/pull/25437#issuecomment-2939788232