Description of problem:

During role assignment creation, global role selection is not creating the role assignment correctly. Based on the error, it is not adding all available clusters to the 
clusterSelection.clusterNames section in the MulticlusterRoleAssignment:

The role assignment creation for kubevirt.io:admin role failed. Error: ResourceError: MulticlusterRoleAssignment.rbac.open-cluster-management.io "role-assignment-1759182301286-gimy5td1t" is invalid: spec.roleAssignments[0].clusterSelection.clusterNames: Invalid value: 0: spec.roleAssignments[0].clusterSelection.clusterNames in body should have at least 1 items

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:

1. Create a role assignment and select Global role
2. Error message will populate on the screen

Actual results:

Role assignment fails to get created.

Expected results:

Role assignment creation should be successful. Global role selection should add all existing managed clusters to the clusterSelection.clusterNames field.

Additional info: