RFR: 8363966: GHA: Switch cross-compiling sysroots to Debian trixie

[Aleksey Shipilev]

On Tue, 2 Sep 2025 12:30:25 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Same as [JDK-8363965](https://bugs.openjdk.org/browse/JDK-8363965), but switching to Debian trixie. We have waited for about a month for it to stabilize, and it seems good to switch now. The benefit of doing this now is making RISC-V sysroot more stable using the same distro as everything else.
> 
> Additional testing:
>  - [x] GHA

Thanks for reviews! Here goes.

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PR Comment: https://git.openjdk.org/jdk/pull/27047#issuecomment-3249086557