refactor: consolidate azure-cni-networkmonitor addon spec

[jackfrancis]

Reason for Change:

This PR consolidates the maintenance of the azure-cni-networkmonitor addon into a single go template-aware YAML file.

Issue Fixed:

Addresses #3188

Requirements:

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

Notes:

[codecov]

Codecov Report

Merging #3189 into master will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #3189      +/-   ##
==========================================
- Coverage   71.24%   71.23%   -0.02%     
==========================================
  Files         147      147              
  Lines       25753    25732      -21     
==========================================
- Hits        18348    18329      -19     
+ Misses       6268     6258      -10     
- Partials     1137     1145       +8     

Impacted Files	Coverage Δ
pkg/engine/templates_generated.go	38.67% <0.00%> (+0.30%)	⬆️
pkg/engine/transform/apimodel_merger.go	70.90% <0.00%> (-5.29%)	⬇️
pkg/operations/kubernetesupgrade/upgradecluster.go	81.17% <0.00%> (-1.53%)	⬇️
pkg/armhelpers/azurestack/azureclient.go	28.68% <0.00%> (-0.78%)	⬇️
pkg/api/convertertoagentpoolonlyapi.go	89.93% <0.00%> (-0.59%)	⬇️
pkg/armhelpers/azureclient.go	35.41% <0.00%> (-0.54%)	⬇️
cmd/deploy.go	62.10% <0.00%> (-0.52%)	⬇️
cmd/upgrade.go	44.32% <0.00%> (-0.25%)	⬇️
pkg/armhelpers/converter.go	90.47% <0.00%> (-0.15%)	⬇️
pkg/armhelpers/azurestack/converter.go	90.47% <0.00%> (-0.15%)	⬇️
... and 4 more

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[mboersma]

/lgtm

[acs-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jackfrancis, mboersma

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