[FLINK-36890] Update observedGeneration on NOOP reconciliation (#923)

The observedGeneration field wasn't updated anymore when the spec update results
in a NOOP reconciliation.

This is a regression of a10fb45 /
#834

Author: mxm

flink-kubernetes-operator/src/main/java/org/apache/flink/kubernetes/operator/reconciler/ReconciliationUtils.java

@@ -546,11 +546,6 @@ public static <SPEC extends AbstractFlinkSpec> void updateReconciliationMetadata
         var lastSpecWithMeta = reconciliationStatus.deserializeLastReconciledSpecWithMeta();
         var newMeta = ReconciliationMetadata.from(resource);
 
-        if (newMeta.equals(lastSpecWithMeta.getMeta())) {
-            // Nothing to update
-            return;
-        }
-
         reconciliationStatus.setLastReconciledSpec(
                 SpecUtils.writeSpecWithMeta(lastSpecWithMeta.getSpec(), newMeta));
         resource.getStatus().setObservedGeneration(resource.getMetadata().getGeneration());

flink-kubernetes-operator/src/test/java/org/apache/flink/kubernetes/operator/reconciler/deployment/ApplicationReconcilerTest.java

@@ -1235,10 +1235,6 @@ public void testUpgradeReconciledGeneration() throws Exception {
         // Submit no-op upgrade
         deployment.getSpec().getFlinkConfiguration().put("kubernetes.operator.test", "value");
         deployment.getMetadata().setGeneration(2L);
-        deployment
-                .getStatus()
-                .getReconciliationStatus()
-                .serializeAndSetLastReconciledSpec(deployment.getSpec(), deployment);
 
         reconciler.reconcile(deployment, context);
         assertEquals(2L, deployment.getStatus().getObservedGeneration());