OCPNODE-3372: Readd omitempty for defaultRuntime as its handled in MCO with additional test cases

Author: ngopalak-redhat

payload-manifests/crds/0000_80_machine-config_01_containerruntimeconfigs.crd.yaml

@@ -53,18 +53,16 @@ spec:
                   runtime.
                 properties:
                   defaultRuntime:
-                    default: ""
                     description: |-
                       defaultRuntime is the name of the OCI runtime to be used as the default for containers.
-                      Allowed values are `runc`, `crun`, and omitted (`""`).
+                      Allowed values are `runc` and `crun`.
                       When set to `runc`, OpenShift will use runc to execute the container
                       When set to `crun`, OpenShift will use crun to execute the container
                       When omitted, this means no opinion and the platform is left to choose a reasonable default,
                       which is subject to change over time. Currently, the default is `crun`.
                     enum:
                     - crun
                     - runc
-                    - ""
                     type: string
                   logLevel:
                     description: |-