selftests/bpf: fix ct status check in bpf_nf selftests

selftests/bpf: fix ct status check in bpf_nf selftests

Check properly the connection tracking entry status configured running
bpf_ct_change_status kfunc.
Remove unnecessary IPS_CONFIRMED status configuration since it is
already done during entry allocation.

Fixes: 6eb7fba007a7 ("selftests/bpf: Add tests for new nf_conntrack kfuncs")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/813a5161a71911378dfac8770ec890428e4998aa.1662623574.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>