properly copy parent roles when migrating v1 SSH creds to SSH + Vault

see: #7050

awx/main/migrations/_credentialtypes.py

@@ -125,6 +125,11 @@ def migrate_to_v2_credentials(apps, schema_editor):
                 if any([getattr(cred, field) for field in ssh_type.defined_fields]):
                     new_cred.save(force_insert=True)
 
+                    # copy parent roles
+                    for role_type in ('read_role', 'admin_role', 'use_role'):
+                        for role in getattr(cred, role_type).parents.all():
+                            getattr(new_cred, role_type).parents.add(role)
+
                     for jt in job_templates:
                         jt.credential = new_cred
                         jt.save()