test/helpers: truncate the output of logs to console
test/helpers: truncate the output of logs to console

To avoid having a ton of logs dumped to console, just give the last 50 lines.
If for some reason there are tons of logs created by Cilium (i.e., > 1 GB)
this will reduce the load on Jenkins.

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

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