Change default options in quark-mon(8)

If you run quark-mon with default values, it will silently fallback to kprobes, this is terrible.
It should default to ebpf, and the user should be required to pass -k for kprobes.
If the user selects features that are not present in kprobes, say QQ_FILE, it should fail instead of just silently load.
If we change this, quark-test(8) should be changed as well, as -k and -b should behave the same on both.

cc @nicholasberlin since we discussed this at some point