chore(oidc): graduate webkey to stable (#10122)

# Which Problems Are Solved

Stabilize the usage of webkeys.

# How the Problems Are Solved

- Remove all legacy signing key code from the OIDC API
- Remove the webkey feature flag from proto
- Remove the webkey feature flag from console
- Cleanup documentation

# Additional Changes

- Resolved some canonical header linter errors in OIDC
- Use the constant for `projections.lock` in the saml package.

# Additional Context

- Closes #10029
- After #10105
- After #10061

console/src/assets/i18n/zh.json

@@ -1642,8 +1642,6 @@
       "ENABLEBACKCHANNELLOGOUT_DESCRIPTION": "Back-Channel 注销实现了 OpenID Connect Back-Channel Logout 1.0，可用于通知客户端在 OpenID 提供商处终止会话。",
       "PERMISSIONCHECKV2": "权限检查 V2",
       "PERMISSIONCHECKV2_DESCRIPTION": "如果启用该标志，您将能够使用新的 API 及其功能。",
-      "WEBKEY": "Web 密钥",
-      "WEBKEY_DESCRIPTION": "如果启用该标志，您将能够使用新的 API 及其功能。",
       "STATES": {
         "INHERITED": "继承",
         "ENABLED": "已启用",