Description of problem:

In ROSA wizard step ,user has specified a longer name (ex:poppoppoppoppoppoppoppoppoppoppoppop) and reached to cluster roles and operator step. The auto generated "Custom operator roles prefix" seems valid but when user select the existing one and deleted then the auto generated "Custom operator roles prefix" value seems invalid due to character limit. This is wrong and always auto generated "Custom operator roles prefix" should be valid.

See the recording CustomPrefixIssuesLongerNames.mp4

How reproducible:

always

Steps to Reproduce:

1. Open OCM UI staging.
2. Launch ROSA wizard.
3. Fill all required fields from each step and reach to "Cluster details" step.
4. Keep a long cluster name (ex: poppoppoppoppoppoppoppoppoppoppoppop) and click "Next"
5. Fill all required definitions and reach to  "Cluster roles and operator" step.
6. Select the "Custom operator roles prefix" value in text box and delete it.
7. See the behavior of newly auto generated "Custom operator roles prefix" value.

Actual results:

At Step 7, The newly auto generated "Custom operator roles prefix" value thrown invalid field validation error.

Expected results:

The newly auto generated "Custom operator roles prefix" value should be valid one within the field restrictions.