Remove vestigial inline authzConfig ConfigMap and volume mount

Background

The operator never sets RunConfig.AuthzConfigPath, so the standalone authz ConfigMap the operator materializes from spec.authzConfig (via EnsureAuthzConfigMap) and mounts at /etc/toolhive/authz (via GenerateAuthzVolumeConfig) is never read. Enforcement happens entirely through the authz config embedded in the RunConfig (addAuthzInlineConfigOptions -> WithAuthzConfig), which the proxy reads from /etc/runconfig/runconfig.json.

The equivalent ref path (spec.authzConfigRef) was removed in #5564 (commit "Stop materializing authzConfigRef into an unread ConfigMap"). The inline path is equally vestigial but pre-existing, so it was left untouched there to keep that change scoped.

Originally flagged by @jhrozek in review of #5563 (the inline GenerateAuthzVolumeConfig is "equally unread").

Scope

• Remove the inline authz ConfigMap materialization (EnsureAuthzConfigMap) and its volume mount (GenerateAuthzVolumeConfig) from mcpserver_controller.go and mcpremoteproxy_controller.go / mcpremoteproxy_deployment.go.
• Delete the helpers and their tests once unused.
• Confirm nothing reads the mounted file (no AuthzConfigPath is ever set in the operator path).

NOTE: the user-supplied authzConfig.type: configMap input (read via LoadAuthzConfigFromConfigMap) is a separate, genuinely-read mechanism — do not remove that.

Tracked as a follow-up to #5564.

Start in mcpserver_controller.go and mcpremoteproxy_controller.go or mcpremoteproxy_deployment.go, then locate EnsureAuthzConfigMap, GenerateAuthzVolumeConfig, and their tests. Remove the unused materialization and mount, confirm the operator never sets AuthzConfigPath, and run the affected tests while preserving LoadAuthzConfigFromConfigMap.