Availability set deprecation

[kon-angelo]

How to categorize this PR?

/area control-plane /kind enhancement /platform azure

What this PR does / why we need it:

• Deprecate Availability-Set based shoots
• Make VMSS-FLex (VMO) the default for non-zonal clusters
• Create a migration path based on https://learn.microsoft.com/en-us/azure/virtual-network/ip-services/public-ip-basic-upgrade-guidance to migrate AS to VMO shoots.

Which issue(s) this PR fixes: Fixes #

Special notes for your reviewer:

Release note:

Disable the creation of Availability-Set-based shoots.

VMSS-Flex based shoots are not the default deployment for non-zonal shoots.

Introduce an annotation to migrate the availability-set shoots to VMSS-Flex shoots.

[kon-angelo]

/test

[testmachinery[bot]]

Testrun: e2e-xn69g Workflow: e2e-xn69g-wf Phase: Succeeded

+---------------------+---------------------------+-----------+----------+
|        NAME         |           STEP            |   PHASE   | DURATION |
+---------------------+---------------------------+-----------+----------+
| infrastructure-test | infra-flow-test           | Succeeded | 21m14s   |
| infrastructure-test | infra-flow-migration-test | Succeeded | 26m21s   |
| bastion-test        | bastion-test              | Succeeded | 9m4s     |
| infrastructure-test | infrastructure-test       | Succeeded | 23m8s    |
+---------------------+---------------------------+-----------+----------+