Description of problem:

In ROSA Hypershift wizard flow, under machine pool step, user has selected a VPC ,added and selected couple of machine pools with private subnets. Once user change the initially selected VPC then there were few leftover definitions seen as part of the private subnet fields in machine pool area. This looks wrong and we need to clear the previous selection when new VPC selected by the user.
See the recording VPCSelectionVsPrivateSubnetIssue.mp4

How reproducible:

always

Steps to Reproduce:

1. Open OCM UI staging 
2. Launch https://console.dev.redhat.com/openshift/create/rosa/wizard?rosaV2=true 
3. Select the control plane as hosted and reach to "Machine pool" step.
4. Select a VPC and add couple of machine pools
5. Select private subnet for each machine pool.
6. Change the VPC value from the drop-down.
7. See the behavior of the private subnet fields

Actual results:

At Step 7, The previously selected private subnet definition is left after the selection of new VPC definition.

Expected results:

All previously selected private subnet definition should be cleared once user select or switch different VPC value.