without specifying "kmsKeyServiceAccount" for controlPlane leads to creating bootstrap and control-plane machines failure

4.16.0-0.nightly-multi-2024-06-12-211551

Always

1. "create install-config" and then insert disk encryption settings, but not set "kmsKeyServiceAccount" for controlPlane (see [2])
2. "create cluster" (see [3])

"create cluster" failed with below error: 

ERROR failed to fetch Cluster: failed to generate asset "Cluster": failed to create cluster: failed to create control-plane manifest: GCPMachine.infrastructure.cluster.x-k8s.io "jiwei-0613d-capi-84z69-bootstrap" is invalid: spec.rootDiskEncryptionKey.kmsKeyServiceAccount: Invalid value: "": spec.rootDiskEncryptionKey.kmsKeyServiceAccount in body should match '[-_[A-Za-z0-9]+@[-_[A-Za-z0-9]+.iam.gserviceaccount.com

Installation should succeed.

FYI the QE test case: 

OCP-61160 - [IPI-on-GCP] install cluster with different custom managed keys for control-plane and compute nodes https://polarion.engineering.redhat.com/polarion/#/project/OSE/workitem?id=OCP-61160