Description of problem:

In ROSA classic wizard flow,  Under Install into existing VPC from networking > configuration step. Once the user selected the VPC , availability zones, filled with both private and public subnet ID fields  and performed a refresh action on VPC . Due to this action selected VPC value is cleared along with  availability zones, filled with both private and public subnet ID definition. This is not a great example for user experience perspective.

Suggestions are

1. Do not clear the selected VPC  value  from the field in case previously selected VPC is available.
2. Keep the other fields (availability zones, filled with both private and public subnet ID fields ) are enabled with existing value.
3. Do clear the selected VPC value from the field in case previously selected VPC is not present from backend request.
4. Do clear all the fields and disable those until user chooses a valid VPC in step3

How reproducible:

always

Steps to Reproduce:

1. Open OCM UI staging.
2. Open ROSA wizard and choose control plane as Classic.
3. Go to Networking > configuration step.
4. Check the option "Install into an existing VPC".
5. Select a VPC and select Availaibility zone.
6. Input the private subnet ID and public subnet ID values.
7. Click "Refresh" button.
8. See the behavior.

Actual results:

At step 8, The selected VPC value is cleared from the field and all other fields such as  availability zones, filled with both private and public subnet ID are  also cleared. This behavior user to force to select VPC and input already entered definition again (if the VPC definition already exists).  

Expected results:

Please see the description.