MB-11286: don't exclude dead childs in set_dynamic_children

Because excluding dead children means that if we're in the middle of
restarting some child, then we can incorrectly skip stopping even if
it's not member of passed list of childs.

Change-Id: I41dbb99a1cdd214838511cd7652b7cc89e3dd115
Reviewed-on: http://review.couchbase.org/37990
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>