agent: Provide better error message when ipsec setup fails
agent: Provide better error message when ipsec setup fails

This error was not useful:
```
level=fatal msg="Error while creating daemon" error="open : no such file or directory" subsys=daemon
```

Signed-off-by: Thomas Graf <5f50a84c1fa3bcff146405017f36aec1a10a9e38@cilium.io>

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