pkg/logging: disable timestamp by default
pkg/logging: disable timestamp by default

Do not have logrus add the timestamp for the log message; rely upon the
logging framework being used external to Cilium to provide this (e.g.,
journalctl).

Signed-off by: Ian Vernon <ian@cilium.io>

eloycoto/cilium,cilium-team/cilium,eloycoto/cilium,tklauser/cilium,tgraf/cilium,michi-covalent/cilium,tklauser/cilium,scanf/cilium,scanf/cilium,scanf/cilium,tklauser/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,cilium-team/cilium,michi-covalent/cilium,eloycoto/cilium,eloycoto/cilium,tklauser/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium,scanf/cilium,scanf/cilium,eloycoto/cilium,michi-covalent/cilium,tklauser/cilium,scanf/cilium,eloycoto/cilium,eloycoto/cilium,cilium/cilium,tgraf/cilium,michi-covalent/cilium,tgraf/cilium,scanf/cilium,cilium/cilium,tgraf/cilium