typo in 4.14/4.15 manifests_test.go

Description of problem:

found typo in 4.14/4.15 branch when review PR: https://github.com/openshift/cluster-monitoring-operator/pull/2073

example typo in 4.14 branch

https://github.com/openshift/cluster-monitoring-operator/blob/release-4.14/pkg/manifests/manifests_test.go

1. systemd unit pattern valiation error
valiation should be validation

2. enable systemd collector with invalid units parttern
parttern should be pattern

3. t.Fatalf("invalid secret namepace, got %s, want %s", s.Namespace, "openshift-user-workload-monitoring")
namepace should be namespace

4. spread contraints
should be spread constraints

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

4.14/4.15

How reproducible:

always

I remember we've added golang-lint to repo, it should find the errors