fix: enableEncryptionWithExternalKms with master VMSS missing objectID

[CecileRobertMichon]

Reason for Change:

Restore CreateKeyVaultVMSS to the behavior it had before the template refactor for enableEncryptionWithExternalKms. Compare with:
https://github.com/Azure/aks-engine/blob/release-v0.31.0/parts/k8s/kubernetesmasterresourcesvmss.t#L76

Issue Fixed:

Fixes #1034

Requirements:

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

Notes:

[CecileRobertMichon]

/hold

for manual validation

[CecileRobertMichon]

@davidmatson FYI

[jackfrancis]

So this fixes the case when useManagedIdentity is false?

[CecileRobertMichon]

So this fixes the case when useManagedIdentity is false?

Correct

[codecov]

Codecov Report

Merging #1194 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master   #1194      +/-   ##
=========================================
- Coverage    74.7%   74.7%   -0.01%     
=========================================
  Files         128     128              
  Lines       18235   18234       -1     
=========================================
- Hits        13622   13621       -1     
  Misses       3829    3829              
  Partials      784     784

[jackfrancis]

lgtm

[CecileRobertMichon]

/hold cancel

validated

[mboersma]

/lgtm

[acs-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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