RFR: 8357913: Add `@Stable` to BigInteger and BigDecimal

[Per Minborg]

On Sun, 25 May 2025 22:35:56 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

src/java.base/share/classes/java/math/BigDecimal.java line 4317:

> 4315:     };
> 4316: 
> 4317:     @Stable

This one is a bit dangerous as it can be reassigned. I think we should not mark this array @Stable unless we have analysed in detail the implications thereof.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25437#discussion_r2111639918