Fix private endpoint deletion in CAPZ

[nprokopic]

Motivation

Private endpoint deletion in CAPZ is broken (or the deletion implementation is incomplete). When a private endpoint is deleted in AzureCluster CR, the private endpoint resource in Azure is not deleted.

TODO

• When a private endpoint is deleted in AzureCluster CR, delete that private endpoint resource in Azure.
• Test the outcome. Write needed unit/integration tests in CAPZ, verify in Giant Swarm test clusters.
• Check with CAPZ community if this fix should be contributed to CAPZ upstream, considering that private endpoint implementation will soon switch to use ASO.
• Communicate to Team Phoenix if the fix will be contributed to upstream or not, and explain the reasoning.

Outcome

• When a private endpoint is deleted in AzureCluster CR, the private endpoint resource is deleted in Azure.

[nprokopic]

Fixed here giantswarm/cluster-api-provider-azure#19.

We don't want to contribute this to upstream CAPZ, as CAPZ will start using azure-service-operator which will change the underlying implementation, which would make our fix obsolete.