LU-17899 scripts: Fix lsvcgss service startup dependencies

LU-17899 scripts: Fix lsvcgss service startup dependencies

A VM was found which did not start networking on boot due to a
circular dependency between it and the lsvcgss service description:

 systemd: network-online.target: Found ordering cycle on network.target
 systemd: network-online.target: Found dependency on lsvcgss.service
 systemd: network-online.target: Found dependency on network-online.target
 systemd: network-online.target: Job network.target/stop deleted to
      break ordering cycle starting with network-online.target/stop

The lsvcgss.service file include "WantedBY=network.target", however
since "network.target" can start before "network-online.target" this
can cause service order issues on boot.

Instead "WantedBy=multi-user.target" is used, which is common usage
for network based services with RHEL linux.

Test-Parameters: trivial
Fixes: 5e39181b6d8 ("LU-17899 gss: improved systemd unit file for SSK daemon")
Signed-off-by: Frederick Dilger <fdilger@whamcloud.com>
Change-Id: I66a16f0601e8fddbcefad3c0301437d6120d6a27
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56183
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>