datapath: tolerate missing ifaces when setting rp_filter sysctl
datapath: tolerate missing ifaces when setting rp_filter sysctl

At the point where systemd-sysctl applies our rp_filter settings, the host
might not have any cilium_* and/or lxc_* interfaces yet. But systemd-sysctl
treats the failure to resolve these globs as an hard error:

  systemd-sysctl[9354]: Couldn't resolve glob 'net/ipv4/conf/lxc*/rp_filter': No such file or directory
  systemd[1]: systemd-sysctl.service: Main process exited, code=exited, status=1/FAILURE
  systemd[1]: systemd-sysctl.service: Failed with result 'exit-code'.

Adding the `-` option makes systemd-sysctl tolerate such errors.

Fixes: 6432558898aa ("datapath: Create sysctl `rp_filter` overwrite config on agent init")
Suggested-by: Dylan Reimerink <21c0fe750acbe9da3cbcf230785a03c9ae2f4b12@isovalent.com>
Signed-off-by: Julian Wiedmann <a70165cc435925071a1d5d2715fcc7eb04666fa4@isovalent.com>

cilium/cilium,cilium/cilium,cilium/cilium,cilium/cilium,cilium/cilium