Expand support for replication test conversion

Add properties for declaring bucket_types and for automatically
retrieving then information about test clusters needed for replication
tests. This includes automatically naming the test clusters and
determining the cluster leader for each test cluster. This represents
boilerplate that is repeated in many replication tests.

Also begin converting the repl_bucket_types test as a sample and to
test these new features.
Use metadata property and change confirm arity to 1

Change the confirm API to only accept a single input of an
rt_properties record. The metadata formerly passed as the second
parameter to confirm is now in the previously unused metadata property
field. Change all tests that have been converted thus far to the new
API. Also remove an unused properties field from the rt_properties
record.