Make bad copy-mode be an error in runmode-tile.

Making this case harder for a user to ignore so that it is not missed, which can result in no traffic being forwarded.

Passes PR script:
- PR build: https://buildbot.openinfosecfoundation.org/builders/ken-tilera/builds/40
- PR pcaps: https://buildbot.openinfosecfoundation.org/builders/ken-tilera-pcap/builds/46