chore(oidc): remove legacy storage methods (#10061)

# Which Problems Are Solved

Stabilize the optimized introspection code and cleanup unused code.

# How the Problems Are Solved

- `oidc_legacy_introspection` feature flag is removed and reserved.
- `OPStorage` which are no longer needed have their bodies removed.
- The method definitions need to remain in place so the interface
remains implemented.
  - A panic is thrown in case any such method is still called

# Additional Changes

- A number of `OPStorage` methods related to token creation were already
unused. These are also cleaned up.

# Additional Context

- Closes #10027 
- #7822

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>

console/src/assets/i18n/zh.json

@@ -1624,8 +1624,6 @@
     "FEATURES": {
       "LOGINDEFAULTORG": "登录默认组织",
       "LOGINDEFAULTORG_DESCRIPTION": "如果没有设置组织上下文，登录界面将使用默认组织的设置（而不是实例的设置）",
-      "OIDCLEGACYINTROSPECTION": "OIDC 传统内省",
-      "OIDCLEGACYINTROSPECTION_DESCRIPTION": "我们最近出于性能原因重构了内省端点。如果出现意外错误，可以使用此功能回滚到传统实现。",
       "OIDCTOKENEXCHANGE": "OIDC 令牌交换",
       "OIDCTOKENEXCHANGE_DESCRIPTION": "启用 OIDC 令牌端点的实验性 urn:ietf:params:oauth:grant-type:token-exchange 授权类型。令牌交换可用于请求具有较少范围的令牌或模拟其他用户。请参阅安全策略以允许在实例上模拟。",
       "OIDCTRIGGERINTROSPECTIONPROJECTIONS": "OIDC 触发内省投影",