MB-17086: Fix to performance regression.

MB-17086: Fix to performance regression.

Revert "MB-16632: As part of queueDirty schedule a DCP connections notifier task"

This reverts commit fa17728e7ca0c637c84a2208b5decfe7ba7e54f1.

Performance testing showed that a regression has been introduced and that
fa17728 was the cause.

The regression was introduced by some fixes made during review that weren't
re-profiled.

Performance can be improved by making some further changes but the investigation
revealed that performance is actually at its best without fa17728.

Change-Id: I7ac3ff49d0b9ce8563f3a932dd337a58d03a0153
Reviewed-on: http://review.couchbase.org/58380
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>