Change the default timeout for waiting for a connection from pool

During Fetch operation Query Service uses connection pool to KV The time out for that is 30 days non configurable at present.
https://github.com/couchbase/go-couchbase/blob/master/conn_pool.go#L26

Waiting 30 days for a connection to timeout would give the impression that the thread has locked up. A more sane default should be used and this option should be configurable.

It might also be a good idea to see what the official SDK does here if it has pools and match the behaviour.