RFR: 8363965: GHA: Switch cross-compiling sysroots to Debian bookworm

[Aleksey Shipilev]

I have noticed that GHA jobs started to fail when creating ppc64el sysroot. We are using Debian bullseye as the base for sysroots. Debian bullseye is LTS release. Perhaps counter-intuitively, LTS platform support shrinks over the LTS lifetime. Debian wiki: https://wiki.debian.org/LTS/Using -- says:

"Important: The current LTS version is Debian 11 ("bullseye") and will be supported until August 31st, 2026. Supported architectures in Debian 11 LTS are limited to amd64, i386, arm64 and armhf. Users of other architectures are especially encouraged to upgrade to Debian 12 (''bookworm''). "

We should consider switching to Debian bookworm for GHA cross-compiling sysroots. Again, Debian wiki: https://wiki.debian.org/DebianBookworm#Architectures -- says all architectures we need are supported. But actually, RISC-V is still only supported with sid. So, we need to be switching only current bullseye to bookworm, leaving sid as sid. This should change as Debian trixie releases in a few weeks, but we cannot wait for this long. Debian trixie update would be handled in [JDK-8363966](https://bugs.openjdk.org/browse/JDK-8363966).

Additional testing:
 - [ ] GHA

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Commit messages:
 - RISC-V is still on sid
 - Bookworm

Changes: https://git.openjdk.org/jdk/pull/26447/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26447&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8363965
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/26447.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26447/head:pull/26447

PR: https://git.openjdk.org/jdk/pull/26447