add 'schedulerName' to openmpi package.

In Kubernetes default scheduler, scheduling multiple openmpi package will sometimes lead deadlocks as discussed kubeflow/training-operator#165 .

In that case,  user would want to perform gang-scheduling(scheduling a group of pods all-together).  Currently, kube-arbitrator support it.

To achieve that, we need to make 'schedulerName' customizable.

kubeflow/openmpi/prototypes/openmpi.jsonnet

@@ -7,6 +7,7 @@
 // @param secret string Name of secret containing ssh keys.
 // @optionalParam namespace string null Namespace to use for the components. It is automatically inherited from the environment if not set.
 // @optionalParam workers number 4 Number of workers.
+// @optionalParam schedulerName string default-scheduler scheduler name to use for the components.
 
 local k = import "k.libsonnet";
 local openmpi = import "kubeflow/openmpi/all.libsonnet";

kubeflow/openmpi/workloads.libsonnet

@@ -38,7 +38,7 @@
           restartPolicy: "Always",
           terminationGracePeriodSeconds: 30,
           dnsPolicy: "ClusterFirst",
-          schedulerName: "default-scheduler",
+          schedulerName: params.schedulerName,
           volumes: [
             {
               name: "kubeflow-openmpi-secrets",