The x-pack client jar and api jar are exactly the same: the entirety of
x-pack. Since we added the x-pack-transport jar, we no longer really
want the client jar as it is confusing. Additionally, it causes jar hell
when a test for an extension uses the transport client. This change
removes the client jar, and makes the x-pack transport client use the
api jar instead. This sounds odd at first, but since transport client is
going away eventually, it is a stopgap, and works.
closeselastic/elasticsearch#3309
Original commit: elastic/x-pack-elasticsearch@ee7a2c12c0