Description of problem:
In ROSA classic v2 wizard flow> Under machine pool tab, user has initially selected a non supporting compute node type definition from the compute node type dropdown. User has changed the settings to later i.e disabled option "include the types that might be unavailable to your account and region". As a result of this action, previously selected compute node type was gone and dropdown value set to "select instance type" and it is no more considered as a required field and user could move to next step without any compute node type selected and it looks wrong.

See the recordings  ComputeNodeTypeNoSelection.mp4

How reproducible:

always

Steps to Reproduce:

1. Open OCM UI staging.
2. Launch ROSA wizard and select control plane as "Classic"
3. Reach to "Default machine pool" step.
4. Click "Compute node type" dropdown.
5. Enable the "Include the types that might be unavailable to your account and region"
6. Select a compute node type unavailable (shown in yellow exclamation indication).
7. Disable the "Include the types that might be unavailable to your account and region"
8. Click "Next" button and see the behavior.

Actual results:

At step 8, User allowed to move next step although compute node type value is not selected (this is result of action at step7) and field is a required field from wizard.

Expected results:

At step 8, User should not allow to move next  step as compute node type value is not selected  and field is required.