chore: Bump NiFi to 2.9.0

Author: Techassi

stacks/data-lakehouse-iceberg-trino-spark/nifi.yaml

@@ -5,7 +5,7 @@ metadata:
   name: nifi
 spec:
   image:
-    productVersion: 2.7.2
+    productVersion: 2.9.0
   clusterConfig:
     authentication:
       - authenticationClass: nifi-admin-credentials

stacks/nifi-kafka-druid-superset-s3/nifi.yaml

@@ -5,7 +5,7 @@ metadata:
   name: nifi
 spec:
   image:
-    productVersion: 2.7.2
+    productVersion: 2.9.0
   clusterConfig:
     authentication:
       - authenticationClass: nifi-admin-credentials

stacks/signal-processing/nifi.yaml

@@ -5,7 +5,7 @@ metadata:
   name: nifi
 spec:
   image:
-    productVersion: 2.7.2
+    productVersion: 2.9.0
     # TODO (@NickLarsenNZ): Use a versioned image with stackable0.0.0-dev or stackableXX.X.X so that
     # the demo is reproducable for the release and it will be automatically replaced for the release branch.
     custom: oci.stackable.tech/demos/nifi:2.7.2-postgresql