Removed mesos flags from known-flags.txt.

hack/verify-flags/known-flags.txt

@@ -470,19 +470,6 @@ max-outgoing-qps
 max-pods
 max-requests-inflight
 max-unavailable
-mesos-authentication-principal
-mesos-authentication-provider
-mesos-authentication-secret-file
-mesos-cgroup-prefix
-mesos-default-pod-roles
-mesos-executor-cpus
-mesos-executor-mem
-mesos-framework-roles
-mesos-generate-task-discovery
-mesos-launch-grace-period
-mesos-master
-mesos-sandbox-overlay
-mesos-user
 metrics-bind-address
 metrics-path
 min-available