MB-8657 Fix the number of workers to be matched for mix loads

This change fixes the issue for a case where the number of
actual worker threads is not matched with the number of readers
and writers given by the user.

Change-Id: I1c6b1284bd4677af715603d01d1829b6611a87f0
Reviewed-on: http://review.couchbase.org/28325
Reviewed-by: Chiyoung Seo <chiyoung.seo@gmail.com>
Tested-by: Chiyoung Seo <chiyoung.seo@gmail.com>
MB-8861 Schedule a tap connection notification through dispatcher

This change allows us to schedule a notification event for a
given TAP connection through the non-IO dispatcher.

Change-Id: I3ef0ef3c9bcd86293f0114355c064069946c5977
Reviewed-on: http://review.couchbase.org/28334
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Chiyoung Seo <chiyoung.seo@gmail.com>
Merge branch '2.1.1'

* 2.1.1:
  MB-8861 Schedule a tap connection notification through dispatcher
  MB-8657 Fix the number of workers to be matched for mix loads

Conflicts:
	src/workload.cc
	tests/ep_testsuite.cc

Change-Id: Iced1d3c958b2b318c63c075fb2041bcd78c2f78b