[gha] run lldb tests against ds2 on new Linux arm64 runners

[andrurogerz]

Purpose

Increase ds2 test coverage in CI by running the same set of lldb tests we run on Linux x86_64 on the new GitHub Linux arm64 runners.

Overview

• Rename and split the build-linux-lldb job to run on both ubuntu-latest and ubuntu-24.04-arm servers, requiring a few adjustments:
  • Adding a workaround for gha-setup-ninja on the arm runners to explicitly specify platform and version
  • Setting LLVM_TARGETS_TO_BUILD="host" instead of X86
  • Updating to a newer revision of hendrikmuhs/ccache-action that contains this PR that fixes sccache support on the arm runners
• Split the test-linux job to run on both ubuntu-latest and ubuntu-24.04-arm servers, also requiring a few adjustments:
  • Defining new test sets in the matrix for aarch64
  • Excluding install of the gcc-multilib package except when testing i686 since the package is not available on the arm runner
• Add new test exclusion files for the tests that fail on Linux aarch64

Background

Validation

A number of successful CI runs on the andrurogerz/ds2 fork:
https://github.com/andrurogerz/ds2/actions/runs/12918614369
https://github.com/andrurogerz/ds2/actions/runs/12918977240
https://github.com/andrurogerz/ds2/actions/runs/12918978353
https://github.com/andrurogerz/ds2/actions/runs/12918979141
https://github.com/andrurogerz/ds2/actions/runs/12918979966
https://github.com/andrurogerz/ds2/actions/runs/12919474811
https://github.com/andrurogerz/ds2/actions/runs/12919522262