Revert "jwt_authn: Add logic to refetch JWT on KID mismatch (#36458)"

[wbpcode]

Commit Message: Revert "jwt_authn: Add logic to refetch JWT on KID mismatch (#36458)"
Additional Description:

To resolve the frequent jwt test failures. See #37720.

It's merged recently and the implementation of that feature has obvious thread-safty problem and lifetime problem. We can never use TLS as a way to prevent concurrent async fetching and cannot post a task to another thread without any lifetime insurance.

So, reverted it.

Risk Level: low.
Testing:
Docs Changes:
Release Notes:
Platform Specific Features:
[Optional Runtime guard:]
[Optional Fixes #Issue]
[Optional Fixes commit #PR or SHA]
[Optional Deprecated:]
[Optional API Considerations:]

[repokitteh-read-only]

CC @envoyproxy/api-shepherds: Your approval is needed for changes made to (api/envoy/|docs/root/api-docs/).
envoyproxy/api-shepherds assignee is @abeyad
CC @envoyproxy/api-watchers: FYI only for changes made to (api/envoy/|docs/root/api-docs/).

🐱

Caused by: #37763 was opened by wbpcode.

see: more, trace.

[wbpcode]

cc @adisuissa @tyxia

[wbpcode]

cc @arulthileeban

[tyxia]

thanks