9c14a9ab introduced vzNewDomain function to enlist libvirt domain
object before actually creating vz sdk domain. Fix should fix
race on same vz sdk domain added event where libvirt domain object is
enlisted too. But later eb5e9c1e added locked checks for
adding livirtd domain object to list on vz sdk domain added event.
Thus now approach of 9c14a9ab is unnecessary complicated.

  See we have otherwise unuseful prlsdkGetDomainIds function only
to create minimal domain definition to create libvirt domain object.
Also vzNewDomain is difficult to use as it creates partially
constructed domain object.

  Let's move back to original approach where prlsdkLoadDomain do
all the necessary job. Another benefit is that we can now
take driver lock for bare minimum and in single place. Reducing
locking time have small disadvatage of double parsing on race
conditions which is typical if domain is added thru vz driver.
Well we have this double parse inevitably with current vz sdk api
on any domain updates so i would not take it here seriously.

  Performance events subscribtion is done before locked check and
therefore could be done twice on races but this is not the problem.
Signed-off-by: NNikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>