selftests: netfilter: nft_queue.sh: move to lib.sh infra

- switch to socat, like other tests
- use buswait helper to test once listener netns is ready
- do not generate multiple input test files, only generate
  one and use cleanup hook to remove it, like other temporary files.

Signed-off-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/r/20240418152744.15105-2-fw@strlen.de


Signed-off-by: Jakub Kicinski <kuba@kernel.org>