When /etc/systemd/system/scylla-server.service.d/capabilities.conf is not installed, we don't have /etc/systemd/system/scylla-server.service.d/, need to create it. Fixes #3738 Signed-off-by: Takuya ASADA <syuu@scylladb.com> Message-Id: <20180904015841.18433-1-syuu@scylladb.com>