Set events.target_type to project when creating a new project event

See 'target_type' parameter for Events API is nil f... (&19098) for context

Currently, project events are created without a set target_type and target_id. This is causing a problem with our Events RESP API as the target_type filter always gives an empty result for project.

We need to ensure that new events created for projects gets an appropriate target_type.

Implementation Guide

1. Use create_record_event when creating project events in app/services/event_create_service.rb
2. Update methods in app/models/event.rb that uses the absence of target_type to check if a project is nil.

We verified that all events with nil target type is either a project event or push event: https://console.postgres.ai/gitlab/gitlab-production-main/sessions/42844/commands/131183

Reference: !202890 (diffs)