With features like CCR building on the CCS infrastructure, the settings
prefix search.remote makes less sense as the namespace for these remote
cluster settings than does a more general namespace like
cluster.remote. This commit replaces these settings with cluster.remote
with a fallback to the deprecated settings search.remote.
This commit removes the unnecessary transport_client cluster permission
from the role that is used as an example in our documentation. This
permission is not needed to use cross cluster search.