Refactor dotCMS core analytics code

Description

Clean up dotCMS core as part of the migration to the new analytics microservice architecture. dotCMS now only proxies analytics requests to the microservice — the legacy endpoint and token management code are no longer needed.

Changes required:

1. Remove old analytics endpoint — ContentAnalyticsResource.java (line 60 and related methods)
2. Remove token renewal code — AccessTokenRenewJob.java and all related scheduler registrations in DotInitScheduler
3. Create Postman test — Add Postman collection tests for EventAnalyticsProxyResource to verify the proxy endpoint works end-to-end

This cleanup is a prerequisite to the new architecture where dotCMS only proxies requests to the microservice.

Parent epic: #35048

Acceptance Criteria

• ContentAnalyticsResource.java legacy endpoint removed (entry point at line 60 and all associated logic)
• AccessTokenRenewJob.java removed
• All scheduler registrations for token renewal removed from DotInitScheduler
• No compilation errors after removal — no dangling references
• Postman test added for EventAnalyticsProxyResource covering: successful proxy to event manager, auth header forwarding, error passthrough
• Code passes build (./mvnw install -pl :dotcms-core -DskipTests)

Additional Context

• Source task: Task 26 (Core code refactoring) from the improvement plan
• Related branch: issue-34849-Add-dotCMS-Analytics-Proxy-Endpoint-for-/v1/analytics/-to-dot-ca-event-manager
• New proxy entry point: EventAnalyticsProxyResource.java

Start with ContentAnalyticsResource.java, AccessTokenRenewJob.java, DotInitScheduler, and EventAnalyticsProxyResource.java to trace the legacy endpoint, token-renewal registrations, and proxy behavior. Run ./mvnw install -pl :dotcms-core -DskipTests, then use the existing Postman setup to cover successful proxying, auth-header forwarding, and error passthrough. Done means the legacy code and dangling references are gone, the proxy tests exist, and the build passes.