Add topologySpreadConstraints configuration to pod spec. (#2530)

* Add topologySpreadConstraints configuration to pod spec.
* Run update-codegen.sh to add deepcopy for new field to the api.
* Reuse configured TopologySpreadConstraints for logical backup.
* Remove x-kubernetes-preserve-unknown-fields and XPreserveUnknownFields.
* Add topologySpreadConstraint example in the complete manifest.
* Add support for helm chart.
* Add documentation for topologySpreadConstraint.
* Update e2e test to patch topologySpreadConstraints into the postgresqls manifest.
* For e2e test, updated the PVC retention policy to remove redundant PVCs.
* Fix e2e test, expected PVC count in end-to-end test after config changes.

charts/postgres-operator/crds/postgresqls.yaml

@@ -4055,6 +4055,23 @@ spec:
                       type: string
                   type: object
                 type: array
+              topologySpreadConstraints:
+                type: array
+                nullable: true
+                items:
+                  type: object
+                  properties:
+                    maxskew:
+                      type: integer
+                      format: int32
+                      minimum: 1
+                    topologyKey:
+                      type: string
+                    whenUnsatisfiable:
+                      type: string
+                      enum:
+                        - DoNotSchedule
+                        - ScheduleAnyway
               useLoadBalancer:
                 description: |-
                   deprecated load balancer settings maintained for backward compatibility