fix: add nodeSelector for coredns-autoscaler

[chewong]

Reason for Change:

coredns-autoscaler was evicted to a Windows node during an upgrade in https://upstream.jenkins.azure-containers.io/blue/organizations/jenkins/k8s-create-cluster-matrix/detail/k8s-create-cluster-matrix/141/pipeline/271/, causing the test to fail. It looks like it's deployed without a node selector.

Issue Fixed:

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

[jackfrancis]

Thanks!

psss make generate and commit

[codecov]

Codecov Report

Merging #3109 into master will decrease coverage by 0.12%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3109      +/-   ##
==========================================
- Coverage   71.03%   70.90%   -0.13%     
==========================================
  Files         147      147              
  Lines       25553    25509      -44     
==========================================
- Hits        18152    18088      -64     
- Misses       6271     6291      +20     
  Partials     1130     1130              

Impacted Files	Coverage Δ
pkg/engine/templates_generated.go	37.46% <ø> (-0.30%)	⬇️
pkg/api/types.go	94.02% <0.00%> (-0.44%)	⬇️
pkg/api/vlabs/validate.go	79.16% <0.00%> (-0.20%)	⬇️
pkg/api/defaults-custom-cloud-profile.go	85.71% <0.00%> (-0.12%)	⬇️
pkg/api/addons.go	97.73% <0.00%> (-0.11%)	⬇️
pkg/api/converterfromapi.go	93.88% <0.00%> (-0.02%)	⬇️
pkg/api/convertertoapi.go	93.68% <0.00%> (-0.02%)	⬇️
pkg/api/defaults.go	92.41% <0.00%> (-0.01%)	⬇️
pkg/api/k8s_versions.go	100.00% <0.00%> (ø)
... and 1 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 74d7a51...9f61e9d. Read the comment docs.

[jackfrancis]

/lgtm