antctl: fix cluster checker image

The image tag missed "v" when built for a released antctl.

Signed-off-by: Quan Tian <quan.tian@broadcom.com>

pkg/antctl/raw/check/cluster/command.go

@@ -199,7 +199,7 @@ func (t *testContext) setup(ctx context.Context) error {
 
 func getAntreaAgentImage() string {
 	if version.ReleaseStatus == "released" {
-		return fmt.Sprintf("antrea/antrea-agent-ubuntu:%s", version.GetVersion())
+		return fmt.Sprintf("antrea/antrea-agent-ubuntu:%s", version.Version)
 	}
 	return "antrea/antrea-agent-ubuntu:latest"
 }