Description of problem:

Created a OSD AWS (non CCS) cluster, the machine pool contains the default name as worker. User has created a new machine pool for the same cluster with a node count 4. After successful creation of new machine pool, tried to scale down the default worker machine pool to zero. The action failed from UI and indicated below error which is wrong as cluster has already machine pool with node count 4. This issue happens without autoscale and with autoscale features.

See the recordings -  DefaultWorkerNodeScaleDownZeroFailed.mp4

How reproducible:

always

Steps to Reproduce:

1. Open OCM UI staging.
2. Open/Install OSD AWS (non CCS) cluster and go to machine pool tab.
3. Create a new machine pool with name "mp1"  with node count 4.
4. Select "worker" machine pool and scale down the node count to zero.
5. See the behavior.

Actual results:
The default worker node scale down to zero node count fails with above error. This is wrong.

Expected results:

The default worker node should be allowed to scale down to zero since already an existing machine pool with node count 4 available in this case.