test: Display error in case command fails
test: Display error in case command fails

Commands executed with ExecContext() can fail without returning anything
in stderr, for example in case the timeout is reached. In these cases,
we need to print the error message from ExecuteContext() in the logs.

Fixes: 262e7ba ("test: Do not print nil errors in ssh.Exec")
Signed-off-by: Paul Chaignon <a027184a55211cd23e3f3094f1fdc728df5e0500@cilium.io>

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