Refactor ad-connector secrets

[nce]

Currently we have https://github.com/adorsys/ops-k8s-bootstrap/blob/146995ca474fbda9b2568519a863bceca54f2534/bootstrap/modules/dex/kubernetes-resource.tf#L2

As we now only have one microsoft application with multiple redirect urls. We don't need the possibility to access multiple apps. Therefore we only need ONE secret, not one for each cluster.
they should be shared.