run-gnu-tests-smack-ci.sh: Use alpine busybox

[oech3]

Closes #11430

[oech3]

Found 4 SMACK/ROOTFS tests
Running: df/skip-rootfs.sh
  PASS: df/skip-rootfs.sh
Running: id/smack.sh
  PASS: id/smack.sh
Running: mkdir/smack-no-root.sh
  FAIL: mkdir/smack-no-root.sh
Running: mkdir/smack-root.sh
  PASS: mkdir/smack-root.sh

@ChrisDryden Would you suggest alternative source for busybox which does not cause network error?

[xtqqczze]

Could we use busybox-static from apt?

[oech3]

Ubuntu busybox-stattic seems lacking smack support:

Found 4 SMACK/ROOTFS tests
Running: df/skip-rootfs.sh
  FAIL: df/skip-rootfs.sh
Running: id/smack.sh
  FAIL: id/smack.sh
Running: mkdir/smack-no-root.sh
  FAIL: mkdir/smack-no-root.sh
Running: mkdir/smack-root.sh
  FAIL: mkdir/smack-root.sh

[sylvestre]

let's see if it sticks!

[oech3]

It would be nice if we could use Arch Linux runner for this usecase at wsl.yml.