make keycloak DB persisted

In a context where we deploy keycloak PostgreSQL DB on local-path-storage PVs, to ensure that no data is lost on a Cluster API rolling upgrade, we need to:

• deploy multiple postgres pods and enabled postgres replication
• define pod disruption budgets for postgres

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Edit: 24/05 Amonl

We should make it HA, because if node with primary crashes, actual implementation cannot replace primary and thus keycloak resiliency fails