fix: add missing namespace to static Helm templates

[devoncrouse]

What this PR does / why we need it:
A few static templates for the Helm chart are missing a namespace when rendered using helm template, causing failure when applied this way with a non-default namespace:

helm template gatekeeper gatekeeper/gatekeeper -n kube-system | kubectl apply -f -

# Resources created in default namespace:
kubectl get jobs
NAME                                         COMPLETIONS   DURATION   AGE
gatekeeper-update-namespace-label            0/1           39s        39s

kubectl get serviceaccounts
NAME                                  SECRETS   AGE
gatekeeper-update-namespace-label     0         87s

# Reference to service account in chart namespace:
kubectl get clusterrolebinding gatekeeper-update-namespace-label -o yaml
...
subjects:
- kind: ServiceAccount
  name: gatekeeper-update-namespace-label
  namespace: kube-system

# Pod failure in wrong namespace
kubectl describe gatekeeper-update-namespace-label-zrld4
...
  Warning  FailedMount  102s                 kubelet            Unable to attach or mount volumes: unmounted volumes=[cert], unattached volumes=[cert kube-api-access-dnn7h]: timed out waiting for the condition
  Warning  FailedMount  97s (x9 over 3m45s)  kubelet            MountVolume.SetUp failed for volume "cert" : secret "gatekeeper-webhook-server-cert" not found

[maxsmythe]

LGTM

[codecov-commenter]

Codecov Report

Base: 53.58% // Head: 53.61% // Increases project coverage by +0.02% 🎉

Coverage data is based on head (c169cfb) compared to base (0f2c8ea).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2593      +/-   ##
==========================================
+ Coverage   53.58%   53.61%   +0.02%     
==========================================
  Files         120      120              
  Lines       10634    10634              
==========================================
+ Hits         5698     5701       +3     
+ Misses       4502     4500       -2     
+ Partials      434      433       -1     

Flag	Coverage Δ
unittests	53.61% <ø> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...onstrainttemplate/constrainttemplate_controller.go	59.09% <0.00%> (-0.96%)	⬇️
pkg/readiness/object_tracker.go	83.98% <0.00%> (+1.06%)	⬆️
pkg/readiness/list.go	91.17% <0.00%> (+11.76%)	⬆️

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[sozercan]

Thank you! LGTM