tests: (lsfd) adjust the output for unix datagram sockets already connected

tests: (lsfd) adjust the output for unix datagram sockets already connected

Though older kernels report such sockets as "unconnected" via /proc/net/unix,
the newer kernels report them as "connected". The change is introduced in
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=83301b5367a98c17ec0d76c7bc0ccdc3c7e7ad6d

This caused a failure in a test case. To avoid the failure,
this change rewrites "unconnected" in the lsfd's output to "connected".

Signed-off-by: Masatake YAMATO <yamato@redhat.com>