selftests/bpf: drop the unused kTLS program from test_sockmap

selftests/bpf: drop the unused kTLS program from test_sockmap

With the sockmap + kTLS tests gone, the BPF-side support in test_sockmap
is dead: the tls_sock_map map and bpf_prog3 (which redirected skbs into
it) are no longer referenced. Remove them, along with the now-unused
bpf_write_pass() helper.

bpf_prog3 was progs[2], so renumber the progs[] users in test_sockmap.c:
the sockops program drops to progs[2] and the sk_msg tx programs to
progs[3..7]. Shrink the map/prog arrays from 9 to 8 and drop the
tls_sock_map entry (the last one) from map_names[] to match.

Link: https://patch.msgid.link/20260614014102.461064-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>