[WIP] 🌱 clustermodule: create cluster module when template does not define any server

[chrischdi]

…

What this PR does / why we need it:

This allows to drop the server setting on the VSphereMachineTemplate while preserving ClusterModule functionality.

If server is not defined, we can still create the cluster modules using the fallback which is set at the VSphereCluster.

Only affects govmomi

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 #

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[chrischdi]

/retest

unrelated flake

[k8s-ci-robot]

@chrischdi: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-api-provider-vsphere-e2e-vcsim-govmomi-main	c4f024b	link	true	/test pull-cluster-api-provider-vsphere-e2e-vcsim-govmomi-main

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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