chore(kafka): meta add allow_parameters

Author: jianxiaoguo

addons/kafka/3.6/meta.yaml

@@ -15,6 +15,9 @@ instances_retrievable: true
 bindings_retrievable: true
 plan_updateable: true
 allow_parameters:
+- name: "extraEnvVars"
+  required: false
+  description: "extraEnvVars config for values.yaml"
 - name: "listeners.client.protocol"
   required: false
   description: "listeners client protocol config for values.yaml"