small fixture change for couchbase compatability

if a database doesn't easily allow for sorting by time of entry, and instead enforces
sorting by id ascii value (*cough* couchbase *cough*), then an id of 12345 makes following
test (query1) fail - because res[0] will doc with id 12345 instead of intended doc. 
Changing to zxy ensures no breaking changes for other stores, but allows couchbase store to pass