🐛 Use vmType "vmss" in every template to allow mixed mode

[CecileRobertMichon]

What this PR does / why we need it: Following conversation in kubernetes-sigs/cloud-provider-azure#338, this is to allow cloud-provider to be able to work with clusters that have both Machines and MachinePools (ie. VMAS and VMSS).

NAME                            STATUS   ROLES    AGE     VERSION
capz-control-plane-6rhzn   Ready    master   27m     v1.18.3
capz-control-plane-nvscv   Ready    master   20m     v1.18.3
capz-control-plane-qs6c8   Ready    master   25m     v1.18.3
capz-md-0-hftcw            Ready    <none>   25m     v1.18.3
capz-md-0-tdlds            Ready    <none>   25m     v1.18.3
capz-mp-0000000            Ready    <none>   6m13s   v1.18.3
capz-mp-0000002            Ready    <none>   6m13s   v1.18.3

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

:bug: Use vmType "vmss" in every template to allow clusters that have both Machines and MachinePools

[CecileRobertMichon]

/hold
/assign @feiskyer

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CecileRobertMichon

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[CecileRobertMichon]

/retest
/hold cancel
Got confirmation from @feiskyer kubernetes-sigs/cloud-provider-azure#338 (comment)
/assign @devigned

[devigned]

/lgtm

So glad you were able to get clarity on this.