Description of the issue

The OCMUI smoke OSD cluster creation tests are failing due to the unavailability of custom GCP instance types referenced in the spec definitions.
To avoid these failures, we should replace the custom instance types with supported standard GCP machine types (for example, e2-standard-4) that are available across the target regions

Test run details 
https://github.com/RedHatInsights/uhc-portal/actions/runs/21469158791