CA: enable the DRA feature gate whenever the DRA flag is passed

This is needed so that the scheduler code correctly includes and
executes the DRA plugin.

We could just use the feature gate instead of the DRA flag in CA
(the feature gates flag is already there, just not really used),
but I guess there could be use-cases for having DRA enabled in the
cluster but not in CA (e.g. DRA being tested in the cluster, CA only
operating on non-DRA nodes/pods).

cluster-autoscaler/main.go

@@ -42,6 +42,7 @@ import (
 	"k8s.io/autoscaler/cluster-autoscaler/simulator/clustersnapshot/store"
 	"k8s.io/autoscaler/cluster-autoscaler/simulator/framework"
 	"k8s.io/autoscaler/cluster-autoscaler/simulator/scheduling"
+	"k8s.io/kubernetes/pkg/features"
 	kubelet_config "k8s.io/kubernetes/pkg/kubelet/apis/config"
 
 	"k8s.io/apimachinery/pkg/api/meta"
@@ -691,6 +692,15 @@ func main() {
 	featureGate.AddFlag(pflag.CommandLine)
 	kube_flag.InitFlags()
 
+	// If the DRA flag is passed, we need to set the DRA feature gate as well. The selection of scheduler plugins for the default
+	// scheduling profile depends on feature gates, and the DRA plugin is only included if the DRA feature gate is enabled. The DRA
+	// plugin itself also checks the DRA feature gate and doesn't do anything if it's not enabled.
+	if *enableDynamicResourceAllocation && !featureGate.Enabled(features.DynamicResourceAllocation) {
+		if err := featureGate.SetFromMap(map[string]bool{string(features.DynamicResourceAllocation): true}); err != nil {
+			klog.Fatalf("couldn't enable the DRA feature gate: %v", err)
+		}
+	}
+
 	leaderElection := defaultLeaderElectionConfiguration()
 	leaderElection.LeaderElect = true
 	componentopts.BindLeaderElectionFlags(&leaderElection, pflag.CommandLine)