fix: upgrade broken for VMAS + managed identities

[jadarsie]

Reason for Change:

Upgrade fails for VMAS clusters if its VMs own a roleAssignment resource.

The problem is that NormalizeResourcesForK8sMasterUpgrade is not filtering roleAssignments resources and ARM complains because these roleAssignments resources depend on missing VM resources.

stdout message:

INFO[0005] Starting ARM Deployment master-20-11-10T15.11.09-1247996574 in resource group upgrade. This will take some time... 
INFO[0006] Error creating upgraded master VM with index: 0 
Error: upgrading cluster: resources.DeploymentsClient#CreateOrUpdate: Failure sending request: StatusCode=400 -- Original Error: Code="InvalidTemplate" Message="Deployment template validation failed: 'The resource 'Microsoft.Compute/virtualMachines/k8s-linuxpool-25762572-0' is not defined in the template. Please see https://aka.ms/arm-template for usage details.'." AdditionalInfo=[{"info":{"lineNumber":0,"linePosition":0,"path":""},"type":"TemplateViolation"}]

Notes:

• Fixed what I think is a problem with the existing tests (nodepool name typo).
• Added a new test to truly validate NormalizeResourcesForK8sMasterUpgrade when upgrading master nodes

Credit Where Due:

Does this change contain code from or inspired by another project?

• No
• Yes

Requirements:

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

[codecov]

Codecov Report

Merging #4021 (13e6c61) into master (c309c3f) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #4021      +/-   ##
==========================================
+ Coverage   73.69%   73.72%   +0.03%     
==========================================
  Files         147      147              
  Lines       23164    23177      +13     
==========================================
+ Hits        17070    17087      +17     
+ Misses       4979     4976       -3     
+ Partials     1115     1114       -1     

Impacted Files	Coverage Δ
...g/operations/kubernetesupgrade/upgradeagentnode.go	47.88% <ø> (ø)
.../operations/kubernetesupgrade/upgrademasternode.go	42.55% <ø> (ø)
pkg/engine/transform/transform.go	71.76% <100.00%> (+2.09%)	⬆️

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[jackfrancis]

do you mean if agentPoolsToPreserve has a length of 0?

[jadarsie]

you are right, I wrote it with this in mind

https://github.com/Azure/aks-engine/blob/v0.57.0/pkg/operations/kubernetesupgrade/upgrader.go#L201

[jackfrancis]

👍

[jackfrancis]

/lgtm

[acs-bot]

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