Changes to platform fields e.g. aws instance type doesn't trigger a rolling upgrade

Always

1. Create a hostedCluster with nodepool on AWS
2. Change the instance type field on the nodepool spec.platfrom.aws

Machines are not restarted and the instance type didn't change

Machines are recreated with the new instance type

This is a result of the recent changes to CAPI which introduced in-place propagation to labels and annotations
Soultion:
MachineTemplate name should not be constant and should change with each spec change, so that spec.infraRef in the MachineDeployment is updated and a rolling upgrade is triggered.