the elb naming conventions: inbound NAT pool, backend pool, and inbound NAT port range allocations per pool

[JaydenLiang]

to be a long term upgrading compatibility consideration, the elb naming conventions and the inbound NAT port range allocations should be well chosen.

naming convention:
backend ip pool: subnet name
inbound NAT pool: vmss-vmss name-mapped-port

inbound NAT pool port range allocations:
byol vmss https: 40000 - 49999. 40000 to 40999 (first 1000 port) are reserved for the initial deployment.
byol vmss ssh: 50000 - 59999. 50000 to 50999 (first 1000 port in total) are reserved for the initial deployment.
payg vmss https: 20000 - 29999. 20000 to 20999 (first 1000 port) are reserved for the initial deployment.
payg vmss ssh: 30000 - 39999. 30000 to 30999 (first 1000 port in total) are reserved for the initial deployment.