Fix aws bv deployment

[maximenoel8]

What does this PR change ?

• correctly declare the is_server_paygo_instance variable for AWS BV using BYOS image
• update both paygo and byos server to fix the netfconfig package issue ( https://bugzilla.suse.com/show_bug.cgi?id=1220718 ). The current available netconfig package on those images has a bug. The fix is available in the repositories but we need to update those servers . Depends on : Make update a module and call it at the begining of default uyuni-project/sumaform#1541
• add chrony package for sles12 deployment. The salt state is failing to install those packages on sles12
• set data disk to 0, we don't handle this disk creation in aws modules