Reduce DCP (memcached) logging for views

Currently views open and close stream continuously.
DCP logs open/close streams and backfills done for every stream open/close.

While it is good to have this information for streams that do not open and close often (like intra cluster replication stream), there will be huge blow up of logs when we have views and we will soon run into scenario where we start cropping out earlier logs from memcached.log