To make sure start Scylla after network is up, we need to move from
network.target to network-online.target.
Fixes #2337
Signed-off-by: Takuya ASADA <syuu@scylladb.com>
Message-Id: <1493661832-9545-1-git-send-email-syuu@scylladb.com>
(cherry picked from commit 0c81974bc4)