fix(consumer): missed consumer update due to wrong version in cache

[Revolyssup]

Description

Fixes #12393
This PR introduced a critical bug #11840 due to which consumers are not updated until a subsequent update in credentials due to credential version being used even for checking consumer update.

More context on this comment: https://github.com/apache/apisix/pull/11840/files#r2193898420

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)

[Baoyuantop]

Will this pr fixed #12393?

[Revolyssup]

Will this pr fixed #12393?

Yes

[bzp2010]

Truth be told, I didn't understand your modifications. Can you provide more insight? 🤔

[Revolyssup]

• change is backward compatible (If not, please discuss on the APISIX mailing list first)

As this comment explains https://github.com/apache/apisix/pull/11840/files#r2193898420
The version being used in the cache was that of credential.modified index. This means until the credential is modified, we will use stale value from cache.
But in the scenario, where the underlying consumer has been modified, we need to recalculate and not use the old value. Therefore in my changes, I have used credential.modified..consumer.modified as the version, so that even when underlying consumer changes, a resync is triggered.

My changes are a revert of the bug introducing PR + only adding expensive operation (.clone()) in the lrucache callback.

[bzp2010]

Thanks for the explanation, I seem to have run into some GitHub bug that prevents the web page from pinpointing the exact comment you pointed out.
Anyway, I've seen it. I will check the code again.

[membphis]

I don't prefer current code style, it not easy to read

We can put those changing code to one or two seperate functions, and check the return value if it failed

Reducing the nesting depth can make the code more readable.