MONGOID-4276 Increase test client pool size to 3
MONGOID-4276 Increase test client pool size to 3

Welovroi/mongoid,jonhyman/mongoid,Welovroi/mongoid,mongodb/mongoid,mongodb/mongoid,mongodb/mongoid,jonhyman/mongoid,herimedia/mongoid,kay-kim/mongoid,kay-kim/mongoid,herimedia/mongoid