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

[zzambers]

This backport switches sysroot for cross-builds in GHA to debian trixie.

Debian bookworm, which is currently used for sysroot, soon enters LTS (2026-06-11). Then set of supported architectures will be reduced, likely breaking cross-build for some archs in GHA (based on past experience). While list of LTS archs for bookworm has not yet been determined, based on debian older versions, it will likely be just i386, amd64, armhf and arm64.

Github workflows in 8 are very different from newer jdks, so made from scratch in spirit of original change. Only affects GHA.

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8363966 needs maintainer approval

Integration blocker

 ⚠️ Dependency #796 must be integrated first

Issue

• JDK-8363966: GHA: Switch cross-compiling sysroots to Debian trixie (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk8u-dev.git pull/797/head:pull/797
$ git checkout pull/797

Update a local copy of the PR:
$ git checkout pull/797
$ git pull https://git.openjdk.org/jdk8u-dev.git pull/797/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 797

View PR using the GUI difftool:
$ git pr show -t 797

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk8u-dev/pull/797.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back zzambers! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

Webrevs

• 01: Full - Incremental (6567054d)
• 00: Full (6567054d)

[zzambers]

This backport depends on: #796
However I cannot base it on pr/796 right now for some reason. (It does not show up in options, I will try again later)