check_vectors does not check the full template duration

The current implementation of check_vectors only works for g-events and external events, since it relies on some fields (instruments, pipeline, etc) of the events dict that do not exist in a superevent API call.

When I wrote !480 (merged), I didn't fully realize that (side note: I should read my own code more carefully), so !480 (merged) assumed that check_vectors was run on superevents, not g-events. The error handling in that commit meant that it essentially had no effect in practice, since every event.get('preferred_event') call would return None.