CLOUDSTACK-4048:[GSLB] Failed to assign more than one LB rule to a GSLB rule that is
created with gslbmethod=leastconn

Netscaler nitro api to add gslb virtual servers fails for some reason if
both netmask and round robin methods are specified. So working around
with settign netmask to be null while updating vserver.
CLOUDSTACK-4075: User unable to archive events
No need to cleanup lightweight entities like offerings

Signed-off-by: Prasanna Santhanam <tsp@apache.org>
(cherry picked from commit 1670aeac360b591f513a76a0c77158672f3e387f)