deck sync/diff not showing updates when auto-gen values change in openid-connect plugin

[Prashansa-K]

Refer: https://kongstrong.slack.com/archives/C046SPHV6AH/p1771544577931339
cache_tokens_salt or session_secret are auto generated values. Ideally, we should error out if these fields are missed.

Note: check schema and kong-ee code for this plugin and compare against namespace validation for RLA plugin