Description of problem:

Performance profile and tuned patch rendering on Day 0 provides a duplicated set of kernel arguments

"systemd.legacy_systemd_cgroup_controller=1",
"systemd.unified_cgroup_hierarchy=0",
"systemd.legacy_systemd_cgroup_controller=1",
"systemd.unified_cgroup_hierarchy=0",

Version-Release number of selected component (if applicable):

    4.15 nightly/ci/stable

How reproducible:

    100%

Steps to Reproduce:

1. Deploy a cluster with performance profile and tuned patch deployed on day-0 as extra-manifests. The openshift release must include the changes made for CNF-10170 for example built with clusterbot as

build openshift/installer#7848

2. The SNO cluster will fail to install with error 
\"rendered-master-fcf20a4afdc64f366ff44a8bbbab203c\" not found"
and MCP master degraded
3. Download from the node missing rendered day-0 machineconfig from /etc/mcs-machine-config-content.json
4. Reinstall the cluster without performance profile / tuned patch and apply them on day 2
5. Take rendered machineconfig and compare to the one from step 3

Actual results:

"systemd.legacy_systemd_cgroup_controller=1",
"systemd.unified_cgroup_hierarchy=0",
"systemd.legacy_systemd_cgroup_controller=1",
"systemd.unified_cgroup_hierarchy=0",

Expected results:
"systemd.legacy_systemd_cgroup_controller=1",
"systemd.unified_cgroup_hierarchy=0",

Additional info: