tests/functional: update the aarch64_virg_gpu images

tests/functional: update the aarch64_virg_gpu images

Update to the most recent aarch64_virt_gpu image. The principle
differences are:

  - target a v8.0 baseline CPU
  - latest vkmark (2025.1)
  - actually uses the rootfs (previously was initrd)
  - rootfs includes more testing tools for interactive use

See README.md in https://fileserver.linaro.org/s/ce5jXBFinPxtEdx for
details about the image creation and the buildroot config.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20250304222439.2035603-8-alex.bennee@linaro.org>