deck always update rate-limiter plugin config even no changes

[jtorkkel]

Kong gateway diff/sync report need to update every rate-limiter plugin config every sync/diff applied

There seems to be undocumented redis_* keys which cause the issue. Either those keys should not be checked or those should be added to render output.
Also sync with merged fails when unused config keys are not set.

Repro steps

Kong 3.6.1.1, Deck 1.25 Linux

Create simple service with route and rate-limiter plugin

services:
- host: localhost
  name: debug_node_log-level
  port: 8001
  protocol: http
  routes:
  - expression: (net.protocol == "http") && (http.method == "GET") && (http.path ==
      "/api/debug/node/log-level")
    name: debug_node_log-level
    priority: 100
plugins:
- config:
    replace:
      uri: /debug/node/log-level
  name: request-transformer
  route: debug_node_log-level
- name: rate-limiting
  service: routes
  config:
    second: 25
    hour: 20000
    policy: local

render config and sync with Kong

Then run validate or sync again

Every time deck indicate needs to update the rate-limit config

updating plugin rate-limiting for service debug_node_log-level  {
   "config": {
     "day": null,
     "error_code": 429,
     "error_message": "API rate limit exceeded",
     "fault_tolerant": true,
     "header_name": null,
     "hide_client_headers": false,
     "hour": 10000,
     "limit_by": "ip",
     "minute": null,
     "month": null,
     "path": null,
     "policy": "local",
     "redis": {
       "database": 0,
       "host": null,
       "password": null,
       "port": 6379,
       "server_name": null,
       "ssl": false,
       "ssl_verify": false,
       "timeout": 2000,
       "username": null
     },
-    "redis_database": 0,
-    "redis_host": null,
-    "redis_password": null,
-    "redis_port": 6379,
-    "redis_server_name": null,
-    "redis_ssl": false,
-    "redis_ssl_verify": false,
-    "redis_timeout": 2000,
-    "redis_username": null,
     "second": 10,
     "sync_rate": -1,
     "year": null
   },
   "enabled": true,
   "id": "89fa57cd-e8eb-4c61-bf06-ec10c1dcde9d",
   "name": "rate-limiting",
   "protocols": [
     "grpc",
     "grpcs",
     "http",
     "https"
   ],
   "service": {
     "id": "f9bef1cb-c742-49f7-8300-3b90b9d54658",
     "name": "debug_node_log-level"
   }
 }
Summary:
  Created: 0
  Updated: 1
  Deleted: 0

Workaround is possible by adding dummy redis_* keys into into declarative rate-limiter plugin config

- name: rate-limiting
  service: routes
  config:
    second: 25
    hour: 20000
    policy: local
    redis_database: 0
    redis_host: null
    redis_password: null
    redis_port: 6379
    redis_server_name: null
    redis_ssl: false
    redis_ssl_verify: false
    redis_timeout: 2000
    redis_username: null

[szesch]

I've also run into this with Kong 3.6 and deck 1.26.0.