MB-24294: Clean-up couch-kvstore openDB with reset=true

MB-24294: Clean-up couch-kvstore openDB with reset=true

The openDB reset flag is only used by the CouchKVStore::reset method
when it calls set-state.

This is no longer required because of the changes in MB-23714 (which
also modified CouchKVStore::reset). There is no need to move the DB
file revision back to 1, it should be monotonically incrementing.

Change-Id: I50ba9873041157923ed99f34623f93ef67527641
Reviewed-on: http://review.couchbase.org/78007
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>